--- a/env/lib/python3.7/site-packages/distlib/wheel.py	Thu May 14 16:47:39 2020 -0400
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,1004 +0,0 @@
-# -*- coding: utf-8 -*-
-#
-# Copyright (C) 2013-2017 Vinay Sajip.
-# Licensed to the Python Software Foundation under a contributor agreement.
-# See LICENSE.txt and CONTRIBUTORS.txt.
-#
-from __future__ import unicode_literals
-
-import base64
-import codecs
-import datetime
-import distutils.util
-from email import message_from_file
-import hashlib
-import imp
-import json
-import logging
-import os
-import posixpath
-import re
-import shutil
-import sys
-import tempfile
-import zipfile
-
-from . import __version__, DistlibException
-from .compat import sysconfig, ZipFile, fsdecode, text_type, filter
-from .database import InstalledDistribution
-from .metadata import Metadata, METADATA_FILENAME, WHEEL_METADATA_FILENAME
-from .util import (FileOperator, convert_path, CSVReader, CSVWriter, Cache,
-                   cached_property, get_cache_base, read_exports, tempdir)
-from .version import NormalizedVersion, UnsupportedVersionError
-
-logger = logging.getLogger(__name__)
-
-cache = None    # created when needed
-
-if hasattr(sys, 'pypy_version_info'):  # pragma: no cover
-    IMP_PREFIX = 'pp'
-elif sys.platform.startswith('java'):  # pragma: no cover
-    IMP_PREFIX = 'jy'
-elif sys.platform == 'cli':  # pragma: no cover
-    IMP_PREFIX = 'ip'
-else:
-    IMP_PREFIX = 'cp'
-
-VER_SUFFIX = sysconfig.get_config_var('py_version_nodot')
-if not VER_SUFFIX:   # pragma: no cover
-    VER_SUFFIX = '%s%s' % sys.version_info[:2]
-PYVER = 'py' + VER_SUFFIX
-IMPVER = IMP_PREFIX + VER_SUFFIX
-
-ARCH = distutils.util.get_platform().replace('-', '_').replace('.', '_')
-
-ABI = sysconfig.get_config_var('SOABI')
-if ABI and ABI.startswith('cpython-'):
-    ABI = ABI.replace('cpython-', 'cp')
-else:
-    def _derive_abi():
-        parts = ['cp', VER_SUFFIX]
-        if sysconfig.get_config_var('Py_DEBUG'):
-            parts.append('d')
-        if sysconfig.get_config_var('WITH_PYMALLOC'):
-            parts.append('m')
-        if sysconfig.get_config_var('Py_UNICODE_SIZE') == 4:
-            parts.append('u')
-        return ''.join(parts)
-    ABI = _derive_abi()
-    del _derive_abi
-
-FILENAME_RE = re.compile(r'''
-(?P<nm>[^-]+)
--(?P<vn>\d+[^-]*)
-(-(?P<bn>\d+[^-]*))?
--(?P<py>\w+\d+(\.\w+\d+)*)
--(?P<bi>\w+)
--(?P<ar>\w+(\.\w+)*)
-\.whl$
-''', re.IGNORECASE | re.VERBOSE)
-
-NAME_VERSION_RE = re.compile(r'''
-(?P<nm>[^-]+)
--(?P<vn>\d+[^-]*)
-(-(?P<bn>\d+[^-]*))?$
-''', re.IGNORECASE | re.VERBOSE)
-
-SHEBANG_RE = re.compile(br'\s*#![^\r\n]*')
-SHEBANG_DETAIL_RE = re.compile(br'^(\s*#!("[^"]+"|\S+))\s+(.*)$')
-SHEBANG_PYTHON = b'#!python'
-SHEBANG_PYTHONW = b'#!pythonw'
-
-if os.sep == '/':
-    to_posix = lambda o: o
-else:
-    to_posix = lambda o: o.replace(os.sep, '/')
-
-
-class Mounter(object):
-    def __init__(self):
-        self.impure_wheels = {}
-        self.libs = {}
-
-    def add(self, pathname, extensions):
-        self.impure_wheels[pathname] = extensions
-        self.libs.update(extensions)
-
-    def remove(self, pathname):
-        extensions = self.impure_wheels.pop(pathname)
-        for k, v in extensions:
-            if k in self.libs:
-                del self.libs[k]
-
-    def find_module(self, fullname, path=None):
-        if fullname in self.libs:
-            result = self
-        else:
-            result = None
-        return result
-
-    def load_module(self, fullname):
-        if fullname in sys.modules:
-            result = sys.modules[fullname]
-        else:
-            if fullname not in self.libs:
-                raise ImportError('unable to find extension for %s' % fullname)
-            result = imp.load_dynamic(fullname, self.libs[fullname])
-            result.__loader__ = self
-            parts = fullname.rsplit('.', 1)
-            if len(parts) > 1:
-                result.__package__ = parts[0]
-        return result
-
-_hook = Mounter()
-
-
-class Wheel(object):
-    """
-    Class to build and install from Wheel files (PEP 427).
-    """
-
-    wheel_version = (1, 1)
-    hash_kind = 'sha256'
-
-    def __init__(self, filename=None, sign=False, verify=False):
-        """
-        Initialise an instance using a (valid) filename.
-        """
-        self.sign = sign
-        self.should_verify = verify
-        self.buildver = ''
-        self.pyver = [PYVER]
-        self.abi = ['none']
-        self.arch = ['any']
-        self.dirname = os.getcwd()
-        if filename is None:
-            self.name = 'dummy'
-            self.version = '0.1'
-            self._filename = self.filename
-        else:
-            m = NAME_VERSION_RE.match(filename)
-            if m:
-                info = m.groupdict('')
-                self.name = info['nm']
-                # Reinstate the local version separator
-                self.version = info['vn'].replace('_', '-')
-                self.buildver = info['bn']
-                self._filename = self.filename
-            else:
-                dirname, filename = os.path.split(filename)
-                m = FILENAME_RE.match(filename)
-                if not m:
-                    raise DistlibException('Invalid name or '
-                                           'filename: %r' % filename)
-                if dirname:
-                    self.dirname = os.path.abspath(dirname)
-                self._filename = filename
-                info = m.groupdict('')
-                self.name = info['nm']
-                self.version = info['vn']
-                self.buildver = info['bn']
-                self.pyver = info['py'].split('.')
-                self.abi = info['bi'].split('.')
-                self.arch = info['ar'].split('.')
-
-    @property
-    def filename(self):
-        """
-        Build and return a filename from the various components.
-        """
-        if self.buildver:
-            buildver = '-' + self.buildver
-        else:
-            buildver = ''
-        pyver = '.'.join(self.pyver)
-        abi = '.'.join(self.abi)
-        arch = '.'.join(self.arch)
-        # replace - with _ as a local version separator
-        version = self.version.replace('-', '_')
-        return '%s-%s%s-%s-%s-%s.whl' % (self.name, version, buildver,
-                                         pyver, abi, arch)
-
-    @property
-    def exists(self):
-        path = os.path.join(self.dirname, self.filename)
-        return os.path.isfile(path)
-
-    @property
-    def tags(self):
-        for pyver in self.pyver:
-            for abi in self.abi:
-                for arch in self.arch:
-                    yield pyver, abi, arch
-
-    @cached_property
-    def metadata(self):
-        pathname = os.path.join(self.dirname, self.filename)
-        name_ver = '%s-%s' % (self.name, self.version)
-        info_dir = '%s.dist-info' % name_ver
-        wrapper = codecs.getreader('utf-8')
-        with ZipFile(pathname, 'r') as zf:
-            wheel_metadata = self.get_wheel_metadata(zf)
-            wv = wheel_metadata['Wheel-Version'].split('.', 1)
-            file_version = tuple([int(i) for i in wv])
-            if file_version < (1, 1):
-                fns = [WHEEL_METADATA_FILENAME, METADATA_FILENAME, 'METADATA']
-            else:
-                fns = [WHEEL_METADATA_FILENAME, METADATA_FILENAME]
-            result = None
-            for fn in fns:
-                try:
-                    metadata_filename = posixpath.join(info_dir, fn)
-                    with zf.open(metadata_filename) as bf:
-                        wf = wrapper(bf)
-                        result = Metadata(fileobj=wf)
-                        if result:
-                            break
-                except KeyError:
-                    pass
-            if not result:
-                raise ValueError('Invalid wheel, because metadata is '
-                                 'missing: looked in %s' % ', '.join(fns))
-        return result
-
-    def get_wheel_metadata(self, zf):
-        name_ver = '%s-%s' % (self.name, self.version)
-        info_dir = '%s.dist-info' % name_ver
-        metadata_filename = posixpath.join(info_dir, 'WHEEL')
-        with zf.open(metadata_filename) as bf:
-            wf = codecs.getreader('utf-8')(bf)
-            message = message_from_file(wf)
-        return dict(message)
-
-    @cached_property
-    def info(self):
-        pathname = os.path.join(self.dirname, self.filename)
-        with ZipFile(pathname, 'r') as zf:
-            result = self.get_wheel_metadata(zf)
-        return result
-
-    def process_shebang(self, data):
-        m = SHEBANG_RE.match(data)
-        if m:
-            end = m.end()
-            shebang, data_after_shebang = data[:end], data[end:]
-            # Preserve any arguments after the interpreter
-            if b'pythonw' in shebang.lower():
-                shebang_python = SHEBANG_PYTHONW
-            else:
-                shebang_python = SHEBANG_PYTHON
-            m = SHEBANG_DETAIL_RE.match(shebang)
-            if m:
-                args = b' ' + m.groups()[-1]
-            else:
-                args = b''
-            shebang = shebang_python + args
-            data = shebang + data_after_shebang
-        else:
-            cr = data.find(b'\r')
-            lf = data.find(b'\n')
-            if cr < 0 or cr > lf:
-                term = b'\n'
-            else:
-                if data[cr:cr + 2] == b'\r\n':
-                    term = b'\r\n'
-                else:
-                    term = b'\r'
-            data = SHEBANG_PYTHON + term + data
-        return data
-
-    def get_hash(self, data, hash_kind=None):
-        if hash_kind is None:
-            hash_kind = self.hash_kind
-        try:
-            hasher = getattr(hashlib, hash_kind)
-        except AttributeError:
-            raise DistlibException('Unsupported hash algorithm: %r' % hash_kind)
-        result = hasher(data).digest()
-        result = base64.urlsafe_b64encode(result).rstrip(b'=').decode('ascii')
-        return hash_kind, result
-
-    def write_record(self, records, record_path, base):
-        records = list(records) # make a copy for sorting
-        p = to_posix(os.path.relpath(record_path, base))
-        records.append((p, '', ''))
-        records.sort()
-        with CSVWriter(record_path) as writer:
-            for row in records:
-                writer.writerow(row)
-
-    def write_records(self, info, libdir, archive_paths):
-        records = []
-        distinfo, info_dir = info
-        hasher = getattr(hashlib, self.hash_kind)
-        for ap, p in archive_paths:
-            with open(p, 'rb') as f:
-                data = f.read()
-            digest = '%s=%s' % self.get_hash(data)
-            size = os.path.getsize(p)
-            records.append((ap, digest, size))
-
-        p = os.path.join(distinfo, 'RECORD')
-        self.write_record(records, p, libdir)
-        ap = to_posix(os.path.join(info_dir, 'RECORD'))
-        archive_paths.append((ap, p))
-
-    def build_zip(self, pathname, archive_paths):
-        with ZipFile(pathname, 'w', zipfile.ZIP_DEFLATED) as zf:
-            for ap, p in archive_paths:
-                logger.debug('Wrote %s to %s in wheel', p, ap)
-                zf.write(p, ap)
-
-    def build(self, paths, tags=None, wheel_version=None):
-        """
-        Build a wheel from files in specified paths, and use any specified tags
-        when determining the name of the wheel.
-        """
-        if tags is None:
-            tags = {}
-
-        libkey = list(filter(lambda o: o in paths, ('purelib', 'platlib')))[0]
-        if libkey == 'platlib':
-            is_pure = 'false'
-            default_pyver = [IMPVER]
-            default_abi = [ABI]
-            default_arch = [ARCH]
-        else:
-            is_pure = 'true'
-            default_pyver = [PYVER]
-            default_abi = ['none']
-            default_arch = ['any']
-
-        self.pyver = tags.get('pyver', default_pyver)
-        self.abi = tags.get('abi', default_abi)
-        self.arch = tags.get('arch', default_arch)
-
-        libdir = paths[libkey]
-
-        name_ver = '%s-%s' % (self.name, self.version)
-        data_dir = '%s.data' % name_ver
-        info_dir = '%s.dist-info' % name_ver
-
-        archive_paths = []
-
-        # First, stuff which is not in site-packages
-        for key in ('data', 'headers', 'scripts'):
-            if key not in paths:
-                continue
-            path = paths[key]
-            if os.path.isdir(path):
-                for root, dirs, files in os.walk(path):
-                    for fn in files:
-                        p = fsdecode(os.path.join(root, fn))
-                        rp = os.path.relpath(p, path)
-                        ap = to_posix(os.path.join(data_dir, key, rp))
-                        archive_paths.append((ap, p))
-                        if key == 'scripts' and not p.endswith('.exe'):
-                            with open(p, 'rb') as f:
-                                data = f.read()
-                            data = self.process_shebang(data)
-                            with open(p, 'wb') as f:
-                                f.write(data)
-
-        # Now, stuff which is in site-packages, other than the
-        # distinfo stuff.
-        path = libdir
-        distinfo = None
-        for root, dirs, files in os.walk(path):
-            if root == path:
-                # At the top level only, save distinfo for later
-                # and skip it for now
-                for i, dn in enumerate(dirs):
-                    dn = fsdecode(dn)
-                    if dn.endswith('.dist-info'):
-                        distinfo = os.path.join(root, dn)
-                        del dirs[i]
-                        break
-                assert distinfo, '.dist-info directory expected, not found'
-
-            for fn in files:
-                # comment out next suite to leave .pyc files in
-                if fsdecode(fn).endswith(('.pyc', '.pyo')):
-                    continue
-                p = os.path.join(root, fn)
-                rp = to_posix(os.path.relpath(p, path))
-                archive_paths.append((rp, p))
-
-        # Now distinfo. Assumed to be flat, i.e. os.listdir is enough.
-        files = os.listdir(distinfo)
-        for fn in files:
-            if fn not in ('RECORD', 'INSTALLER', 'SHARED', 'WHEEL'):
-                p = fsdecode(os.path.join(distinfo, fn))
-                ap = to_posix(os.path.join(info_dir, fn))
-                archive_paths.append((ap, p))
-
-        wheel_metadata = [
-            'Wheel-Version: %d.%d' % (wheel_version or self.wheel_version),
-            'Generator: distlib %s' % __version__,
-            'Root-Is-Purelib: %s' % is_pure,
-        ]
-        for pyver, abi, arch in self.tags:
-            wheel_metadata.append('Tag: %s-%s-%s' % (pyver, abi, arch))
-        p = os.path.join(distinfo, 'WHEEL')
-        with open(p, 'w') as f:
-            f.write('\n'.join(wheel_metadata))
-        ap = to_posix(os.path.join(info_dir, 'WHEEL'))
-        archive_paths.append((ap, p))
-
-        # Now, at last, RECORD.
-        # Paths in here are archive paths - nothing else makes sense.
-        self.write_records((distinfo, info_dir), libdir, archive_paths)
-        # Now, ready to build the zip file
-        pathname = os.path.join(self.dirname, self.filename)
-        self.build_zip(pathname, archive_paths)
-        return pathname
-
-    def skip_entry(self, arcname):
-        """
-        Determine whether an archive entry should be skipped when verifying
-        or installing.
-        """
-        # The signature file won't be in RECORD,
-        # and we  don't currently don't do anything with it
-        # We also skip directories, as they won't be in RECORD
-        # either. See:
-        #
-        # https://github.com/pypa/wheel/issues/294
-        # https://github.com/pypa/wheel/issues/287
-        # https://github.com/pypa/wheel/pull/289
-        #
-        return arcname.endswith(('/', '/RECORD.jws'))
-
-    def install(self, paths, maker, **kwargs):
-        """
-        Install a wheel to the specified paths. If kwarg ``warner`` is
-        specified, it should be a callable, which will be called with two
-        tuples indicating the wheel version of this software and the wheel
-        version in the file, if there is a discrepancy in the versions.
-        This can be used to issue any warnings to raise any exceptions.
-        If kwarg ``lib_only`` is True, only the purelib/platlib files are
-        installed, and the headers, scripts, data and dist-info metadata are
-        not written. If kwarg ``bytecode_hashed_invalidation`` is True, written
-        bytecode will try to use file-hash based invalidation (PEP-552) on
-        supported interpreter versions (CPython 2.7+).
-
-        The return value is a :class:`InstalledDistribution` instance unless
-        ``options.lib_only`` is True, in which case the return value is ``None``.
-        """
-
-        dry_run = maker.dry_run
-        warner = kwargs.get('warner')
-        lib_only = kwargs.get('lib_only', False)
-        bc_hashed_invalidation = kwargs.get('bytecode_hashed_invalidation', False)
-
-        pathname = os.path.join(self.dirname, self.filename)
-        name_ver = '%s-%s' % (self.name, self.version)
-        data_dir = '%s.data' % name_ver
-        info_dir = '%s.dist-info' % name_ver
-
-        metadata_name = posixpath.join(info_dir, METADATA_FILENAME)
-        wheel_metadata_name = posixpath.join(info_dir, 'WHEEL')
-        record_name = posixpath.join(info_dir, 'RECORD')
-
-        wrapper = codecs.getreader('utf-8')
-
-        with ZipFile(pathname, 'r') as zf:
-            with zf.open(wheel_metadata_name) as bwf:
-                wf = wrapper(bwf)
-                message = message_from_file(wf)
-            wv = message['Wheel-Version'].split('.', 1)
-            file_version = tuple([int(i) for i in wv])
-            if (file_version != self.wheel_version) and warner:
-                warner(self.wheel_version, file_version)
-
-            if message['Root-Is-Purelib'] == 'true':
-                libdir = paths['purelib']
-            else:
-                libdir = paths['platlib']
-
-            records = {}
-            with zf.open(record_name) as bf:
-                with CSVReader(stream=bf) as reader:
-                    for row in reader:
-                        p = row[0]
-                        records[p] = row
-
-            data_pfx = posixpath.join(data_dir, '')
-            info_pfx = posixpath.join(info_dir, '')
-            script_pfx = posixpath.join(data_dir, 'scripts', '')
-
-            # make a new instance rather than a copy of maker's,
-            # as we mutate it
-            fileop = FileOperator(dry_run=dry_run)
-            fileop.record = True    # so we can rollback if needed
-
-            bc = not sys.dont_write_bytecode    # Double negatives. Lovely!
-
-            outfiles = []   # for RECORD writing
-
-            # for script copying/shebang processing
-            workdir = tempfile.mkdtemp()
-            # set target dir later
-            # we default add_launchers to False, as the
-            # Python Launcher should be used instead
-            maker.source_dir = workdir
-            maker.target_dir = None
-            try:
-                for zinfo in zf.infolist():
-                    arcname = zinfo.filename
-                    if isinstance(arcname, text_type):
-                        u_arcname = arcname
-                    else:
-                        u_arcname = arcname.decode('utf-8')
-                    if self.skip_entry(u_arcname):
-                        continue
-                    row = records[u_arcname]
-                    if row[2] and str(zinfo.file_size) != row[2]:
-                        raise DistlibException('size mismatch for '
-                                               '%s' % u_arcname)
-                    if row[1]:
-                        kind, value = row[1].split('=', 1)
-                        with zf.open(arcname) as bf:
-                            data = bf.read()
-                        _, digest = self.get_hash(data, kind)
-                        if digest != value:
-                            raise DistlibException('digest mismatch for '
-                                                   '%s' % arcname)
-
-                    if lib_only and u_arcname.startswith((info_pfx, data_pfx)):
-                        logger.debug('lib_only: skipping %s', u_arcname)
-                        continue
-                    is_script = (u_arcname.startswith(script_pfx)
-                                 and not u_arcname.endswith('.exe'))
-
-                    if u_arcname.startswith(data_pfx):
-                        _, where, rp = u_arcname.split('/', 2)
-                        outfile = os.path.join(paths[where], convert_path(rp))
-                    else:
-                        # meant for site-packages.
-                        if u_arcname in (wheel_metadata_name, record_name):
-                            continue
-                        outfile = os.path.join(libdir, convert_path(u_arcname))
-                    if not is_script:
-                        with zf.open(arcname) as bf:
-                            fileop.copy_stream(bf, outfile)
-                        outfiles.append(outfile)
-                        # Double check the digest of the written file
-                        if not dry_run and row[1]:
-                            with open(outfile, 'rb') as bf:
-                                data = bf.read()
-                                _, newdigest = self.get_hash(data, kind)
-                                if newdigest != digest:
-                                    raise DistlibException('digest mismatch '
-                                                           'on write for '
-                                                           '%s' % outfile)
-                        if bc and outfile.endswith('.py'):
-                            try:
-                                pyc = fileop.byte_compile(outfile,
-                                                          hashed_invalidation=bc_hashed_invalidation)
-                                outfiles.append(pyc)
-                            except Exception:
-                                # Don't give up if byte-compilation fails,
-                                # but log it and perhaps warn the user
-                                logger.warning('Byte-compilation failed',
-                                               exc_info=True)
-                    else:
-                        fn = os.path.basename(convert_path(arcname))
-                        workname = os.path.join(workdir, fn)
-                        with zf.open(arcname) as bf:
-                            fileop.copy_stream(bf, workname)
-
-                        dn, fn = os.path.split(outfile)
-                        maker.target_dir = dn
-                        filenames = maker.make(fn)
-                        fileop.set_executable_mode(filenames)
-                        outfiles.extend(filenames)
-
-                if lib_only:
-                    logger.debug('lib_only: returning None')
-                    dist = None
-                else:
-                    # Generate scripts
-
-                    # Try to get pydist.json so we can see if there are
-                    # any commands to generate. If this fails (e.g. because
-                    # of a legacy wheel), log a warning but don't give up.
-                    commands = None
-                    file_version = self.info['Wheel-Version']
-                    if file_version == '1.0':
-                        # Use legacy info
-                        ep = posixpath.join(info_dir, 'entry_points.txt')
-                        try:
-                            with zf.open(ep) as bwf:
-                                epdata = read_exports(bwf)
-                            commands = {}
-                            for key in ('console', 'gui'):
-                                k = '%s_scripts' % key
-                                if k in epdata:
-                                    commands['wrap_%s' % key] = d = {}
-                                    for v in epdata[k].values():
-                                        s = '%s:%s' % (v.prefix, v.suffix)
-                                        if v.flags:
-                                            s += ' %s' % v.flags
-                                        d[v.name] = s
-                        except Exception:
-                            logger.warning('Unable to read legacy script '
-                                           'metadata, so cannot generate '
-                                           'scripts')
-                    else:
-                        try:
-                            with zf.open(metadata_name) as bwf:
-                                wf = wrapper(bwf)
-                                commands = json.load(wf).get('extensions')
-                                if commands:
-                                    commands = commands.get('python.commands')
-                        except Exception:
-                            logger.warning('Unable to read JSON metadata, so '
-                                           'cannot generate scripts')
-                    if commands:
-                        console_scripts = commands.get('wrap_console', {})
-                        gui_scripts = commands.get('wrap_gui', {})
-                        if console_scripts or gui_scripts:
-                            script_dir = paths.get('scripts', '')
-                            if not os.path.isdir(script_dir):
-                                raise ValueError('Valid script path not '
-                                                 'specified')
-                            maker.target_dir = script_dir
-                            for k, v in console_scripts.items():
-                                script = '%s = %s' % (k, v)
-                                filenames = maker.make(script)
-                                fileop.set_executable_mode(filenames)
-
-                            if gui_scripts:
-                                options = {'gui': True }
-                                for k, v in gui_scripts.items():
-                                    script = '%s = %s' % (k, v)
-                                    filenames = maker.make(script, options)
-                                    fileop.set_executable_mode(filenames)
-
-                    p = os.path.join(libdir, info_dir)
-                    dist = InstalledDistribution(p)
-
-                    # Write SHARED
-                    paths = dict(paths)     # don't change passed in dict
-                    del paths['purelib']
-                    del paths['platlib']
-                    paths['lib'] = libdir
-                    p = dist.write_shared_locations(paths, dry_run)
-                    if p:
-                        outfiles.append(p)
-
-                    # Write RECORD
-                    dist.write_installed_files(outfiles, paths['prefix'],
-                                               dry_run)
-                return dist
-            except Exception:  # pragma: no cover
-                logger.exception('installation failed.')
-                fileop.rollback()
-                raise
-            finally:
-                shutil.rmtree(workdir)
-
-    def _get_dylib_cache(self):
-        global cache
-        if cache is None:
-            # Use native string to avoid issues on 2.x: see Python #20140.
-            base = os.path.join(get_cache_base(), str('dylib-cache'),
-                                '%s.%s' % sys.version_info[:2])
-            cache = Cache(base)
-        return cache
-
-    def _get_extensions(self):
-        pathname = os.path.join(self.dirname, self.filename)
-        name_ver = '%s-%s' % (self.name, self.version)
-        info_dir = '%s.dist-info' % name_ver
-        arcname = posixpath.join(info_dir, 'EXTENSIONS')
-        wrapper = codecs.getreader('utf-8')
-        result = []
-        with ZipFile(pathname, 'r') as zf:
-            try:
-                with zf.open(arcname) as bf:
-                    wf = wrapper(bf)
-                    extensions = json.load(wf)
-                    cache = self._get_dylib_cache()
-                    prefix = cache.prefix_to_dir(pathname)
-                    cache_base = os.path.join(cache.base, prefix)
-                    if not os.path.isdir(cache_base):
-                        os.makedirs(cache_base)
-                    for name, relpath in extensions.items():
-                        dest = os.path.join(cache_base, convert_path(relpath))
-                        if not os.path.exists(dest):
-                            extract = True
-                        else:
-                            file_time = os.stat(dest).st_mtime
-                            file_time = datetime.datetime.fromtimestamp(file_time)
-                            info = zf.getinfo(relpath)
-                            wheel_time = datetime.datetime(*info.date_time)
-                            extract = wheel_time > file_time
-                        if extract:
-                            zf.extract(relpath, cache_base)
-                        result.append((name, dest))
-            except KeyError:
-                pass
-        return result
-
-    def is_compatible(self):
-        """
-        Determine if a wheel is compatible with the running system.
-        """
-        return is_compatible(self)
-
-    def is_mountable(self):
-        """
-        Determine if a wheel is asserted as mountable by its metadata.
-        """
-        return True # for now - metadata details TBD
-
-    def mount(self, append=False):
-        pathname = os.path.abspath(os.path.join(self.dirname, self.filename))
-        if not self.is_compatible():
-            msg = 'Wheel %s not compatible with this Python.' % pathname
-            raise DistlibException(msg)
-        if not self.is_mountable():
-            msg = 'Wheel %s is marked as not mountable.' % pathname
-            raise DistlibException(msg)
-        if pathname in sys.path:
-            logger.debug('%s already in path', pathname)
-        else:
-            if append:
-                sys.path.append(pathname)
-            else:
-                sys.path.insert(0, pathname)
-            extensions = self._get_extensions()
-            if extensions:
-                if _hook not in sys.meta_path:
-                    sys.meta_path.append(_hook)
-                _hook.add(pathname, extensions)
-
-    def unmount(self):
-        pathname = os.path.abspath(os.path.join(self.dirname, self.filename))
-        if pathname not in sys.path:
-            logger.debug('%s not in path', pathname)
-        else:
-            sys.path.remove(pathname)
-            if pathname in _hook.impure_wheels:
-                _hook.remove(pathname)
-            if not _hook.impure_wheels:
-                if _hook in sys.meta_path:
-                    sys.meta_path.remove(_hook)
-
-    def verify(self):
-        pathname = os.path.join(self.dirname, self.filename)
-        name_ver = '%s-%s' % (self.name, self.version)
-        data_dir = '%s.data' % name_ver
-        info_dir = '%s.dist-info' % name_ver
-
-        metadata_name = posixpath.join(info_dir, METADATA_FILENAME)
-        wheel_metadata_name = posixpath.join(info_dir, 'WHEEL')
-        record_name = posixpath.join(info_dir, 'RECORD')
-
-        wrapper = codecs.getreader('utf-8')
-
-        with ZipFile(pathname, 'r') as zf:
-            with zf.open(wheel_metadata_name) as bwf:
-                wf = wrapper(bwf)
-                message = message_from_file(wf)
-            wv = message['Wheel-Version'].split('.', 1)
-            file_version = tuple([int(i) for i in wv])
-            # TODO version verification
-
-            records = {}
-            with zf.open(record_name) as bf:
-                with CSVReader(stream=bf) as reader:
-                    for row in reader:
-                        p = row[0]
-                        records[p] = row
-
-            for zinfo in zf.infolist():
-                arcname = zinfo.filename
-                if isinstance(arcname, text_type):
-                    u_arcname = arcname
-                else:
-                    u_arcname = arcname.decode('utf-8')
-                # See issue #115: some wheels have .. in their entries, but
-                # in the filename ... e.g. __main__..py ! So the check is
-                # updated to look for .. in the directory portions
-                p = u_arcname.split('/')
-                if '..' in p:
-                    raise DistlibException('invalid entry in '
-                                           'wheel: %r' % u_arcname)
-
-                if self.skip_entry(u_arcname):
-                    continue
-                row = records[u_arcname]
-                if row[2] and str(zinfo.file_size) != row[2]:
-                    raise DistlibException('size mismatch for '
-                                           '%s' % u_arcname)
-                if row[1]:
-                    kind, value = row[1].split('=', 1)
-                    with zf.open(arcname) as bf:
-                        data = bf.read()
-                    _, digest = self.get_hash(data, kind)
-                    if digest != value:
-                        raise DistlibException('digest mismatch for '
-                                               '%s' % arcname)
-
-    def update(self, modifier, dest_dir=None, **kwargs):
-        """
-        Update the contents of a wheel in a generic way. The modifier should
-        be a callable which expects a dictionary argument: its keys are
-        archive-entry paths, and its values are absolute filesystem paths
-        where the contents the corresponding archive entries can be found. The
-        modifier is free to change the contents of the files pointed to, add
-        new entries and remove entries, before returning. This method will
-        extract the entire contents of the wheel to a temporary location, call
-        the modifier, and then use the passed (and possibly updated)
-        dictionary to write a new wheel. If ``dest_dir`` is specified, the new
-        wheel is written there -- otherwise, the original wheel is overwritten.
-
-        The modifier should return True if it updated the wheel, else False.
-        This method returns the same value the modifier returns.
-        """
-
-        def get_version(path_map, info_dir):
-            version = path = None
-            key = '%s/%s' % (info_dir, METADATA_FILENAME)
-            if key not in path_map:
-                key = '%s/PKG-INFO' % info_dir
-            if key in path_map:
-                path = path_map[key]
-                version = Metadata(path=path).version
-            return version, path
-
-        def update_version(version, path):
-            updated = None
-            try:
-                v = NormalizedVersion(version)
-                i = version.find('-')
-                if i < 0:
-                    updated = '%s+1' % version
-                else:
-                    parts = [int(s) for s in version[i + 1:].split('.')]
-                    parts[-1] += 1
-                    updated = '%s+%s' % (version[:i],
-                                         '.'.join(str(i) for i in parts))
-            except UnsupportedVersionError:
-                logger.debug('Cannot update non-compliant (PEP-440) '
-                             'version %r', version)
-            if updated:
-                md = Metadata(path=path)
-                md.version = updated
-                legacy = not path.endswith(METADATA_FILENAME)
-                md.write(path=path, legacy=legacy)
-                logger.debug('Version updated from %r to %r', version,
-                             updated)
-
-        pathname = os.path.join(self.dirname, self.filename)
-        name_ver = '%s-%s' % (self.name, self.version)
-        info_dir = '%s.dist-info' % name_ver
-        record_name = posixpath.join(info_dir, 'RECORD')
-        with tempdir() as workdir:
-            with ZipFile(pathname, 'r') as zf:
-                path_map = {}
-                for zinfo in zf.infolist():
-                    arcname = zinfo.filename
-                    if isinstance(arcname, text_type):
-                        u_arcname = arcname
-                    else:
-                        u_arcname = arcname.decode('utf-8')
-                    if u_arcname == record_name:
-                        continue
-                    if '..' in u_arcname:
-                        raise DistlibException('invalid entry in '
-                                               'wheel: %r' % u_arcname)
-                    zf.extract(zinfo, workdir)
-                    path = os.path.join(workdir, convert_path(u_arcname))
-                    path_map[u_arcname] = path
-
-            # Remember the version.
-            original_version, _ = get_version(path_map, info_dir)
-            # Files extracted. Call the modifier.
-            modified = modifier(path_map, **kwargs)
-            if modified:
-                # Something changed - need to build a new wheel.
-                current_version, path = get_version(path_map, info_dir)
-                if current_version and (current_version == original_version):
-                    # Add or update local version to signify changes.
-                    update_version(current_version, path)
-                # Decide where the new wheel goes.
-                if dest_dir is None:
-                    fd, newpath = tempfile.mkstemp(suffix='.whl',
-                                                   prefix='wheel-update-',
-                                                   dir=workdir)
-                    os.close(fd)
-                else:
-                    if not os.path.isdir(dest_dir):
-                        raise DistlibException('Not a directory: %r' % dest_dir)
-                    newpath = os.path.join(dest_dir, self.filename)
-                archive_paths = list(path_map.items())
-                distinfo = os.path.join(workdir, info_dir)
-                info = distinfo, info_dir
-                self.write_records(info, workdir, archive_paths)
-                self.build_zip(newpath, archive_paths)
-                if dest_dir is None:
-                    shutil.copyfile(newpath, pathname)
-        return modified
-
-def compatible_tags():
-    """
-    Return (pyver, abi, arch) tuples compatible with this Python.
-    """
-    versions = [VER_SUFFIX]
-    major = VER_SUFFIX[0]
-    for minor in range(sys.version_info[1] - 1, - 1, -1):
-        versions.append(''.join([major, str(minor)]))
-
-    abis = []
-    for suffix, _, _ in imp.get_suffixes():
-        if suffix.startswith('.abi'):
-            abis.append(suffix.split('.', 2)[1])
-    abis.sort()
-    if ABI != 'none':
-        abis.insert(0, ABI)
-    abis.append('none')
-    result = []
-
-    arches = [ARCH]
-    if sys.platform == 'darwin':
-        m = re.match(r'(\w+)_(\d+)_(\d+)_(\w+)$', ARCH)
-        if m:
-            name, major, minor, arch = m.groups()
-            minor = int(minor)
-            matches = [arch]
-            if arch in ('i386', 'ppc'):
-                matches.append('fat')
-            if arch in ('i386', 'ppc', 'x86_64'):
-                matches.append('fat3')
-            if arch in ('ppc64', 'x86_64'):
-                matches.append('fat64')
-            if arch in ('i386', 'x86_64'):
-                matches.append('intel')
-            if arch in ('i386', 'x86_64', 'intel', 'ppc', 'ppc64'):
-                matches.append('universal')
-            while minor >= 0:
-                for match in matches:
-                    s = '%s_%s_%s_%s' % (name, major, minor, match)
-                    if s != ARCH:   # already there
-                        arches.append(s)
-                minor -= 1
-
-    # Most specific - our Python version, ABI and arch
-    for abi in abis:
-        for arch in arches:
-            result.append((''.join((IMP_PREFIX, versions[0])), abi, arch))
-
-    # where no ABI / arch dependency, but IMP_PREFIX dependency
-    for i, version in enumerate(versions):
-        result.append((''.join((IMP_PREFIX, version)), 'none', 'any'))
-        if i == 0:
-            result.append((''.join((IMP_PREFIX, version[0])), 'none', 'any'))
-
-    # no IMP_PREFIX, ABI or arch dependency
-    for i, version in enumerate(versions):
-        result.append((''.join(('py', version)), 'none', 'any'))
-        if i == 0:
-            result.append((''.join(('py', version[0])), 'none', 'any'))
-    return set(result)
-
-
-COMPATIBLE_TAGS = compatible_tags()
-
-del compatible_tags
-
-
-def is_compatible(wheel, tags=None):
-    if not isinstance(wheel, Wheel):
-        wheel = Wheel(wheel)    # assume it's a filename
-    result = False
-    if tags is None:
-        tags = COMPATIBLE_TAGS
-    for ver, abi, arch in tags:
-        if ver in wheel.pyver and abi in wheel.abi and arch in wheel.arch:
-            result = True
-            break
-    return result