--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.7/site-packages/boltons/listutils.py	Sat May 02 07:14:21 2020 -0400
@@ -0,0 +1,328 @@
+# -*- coding: utf-8 -*-
+"""Python's builtin :class:`list` is a very fast and efficient
+sequence type, but it could be better for certain access patterns,
+such as non-sequential insertion into a large lists. ``listutils``
+provides a pure-Python solution to this problem.
+
+For utilities for working with iterables and lists, check out
+:mod:`iterutils`. For the a :class:`list`-based version of
+:class:`collections.namedtuple`, check out :mod:`namedutils`.
+"""
+
+from __future__ import print_function, division
+
+import operator
+from math import log as math_log
+from itertools import chain, islice
+
+try:
+    from typeutils import make_sentinel
+    _MISSING = make_sentinel(var_name='_MISSING')
+except ImportError:
+    _MISSING = object()
+
+try:
+    xrange
+except NameError:
+    # Python 3 compat
+    xrange = range
+
+# TODO: expose splaylist?
+__all__ = ['BList', 'BarrelList']
+
+
+# TODO: comparators
+# TODO: keep track of list lengths and bisect to the right list for
+# faster getitem (and slightly slower setitem and delitem ops)
+
+class BarrelList(list):
+    """The ``BarrelList`` is a :class:`list` subtype backed by many
+    dynamically-scaled sublists, to provide better scaling and random
+    insertion/deletion characteristics. It is a subtype of the builtin
+    :class:`list` and has an identical API, supporting indexing,
+    slicing, sorting, etc. If application requirements call for
+    something more performant, consider the `blist module available on
+    PyPI`_.
+
+    The name comes by way of Kurt Rose, who said it reminded him of
+    barrel shifters. Not sure how, but it's BList-like, so the name
+    stuck. BList is of course a reference to `B-trees`_.
+
+    Args:
+        iterable: An optional iterable of initial values for the list.
+
+    >>> blist = BList(xrange(100000))
+    >>> blist.pop(50000)
+    50000
+    >>> len(blist)
+    99999
+    >>> len(blist.lists)  # how many underlying lists
+    8
+    >>> slice_idx = blist.lists[0][-1]
+    >>> blist[slice_idx:slice_idx + 2]
+    BarrelList([11637, 11638])
+
+    Slicing is supported and works just fine across list borders,
+    returning another instance of the BarrelList.
+
+    .. _blist module available on PyPI: https://pypi.python.org/pypi/blist
+    .. _B-trees: https://en.wikipedia.org/wiki/B-tree
+
+    """
+
+    _size_factor = 1520
+    "This size factor is the result of tuning using the tune() function below."
+
+    def __init__(self, iterable=None):
+        self.lists = [[]]
+        if iterable:
+            self.extend(iterable)
+
+    @property
+    def _cur_size_limit(self):
+        len_self, size_factor = len(self), self._size_factor
+        return int(round(size_factor * math_log(len_self + 2, 2)))
+
+    def _translate_index(self, index):
+        if index < 0:
+            index += len(self)
+        rel_idx, lists = index, self.lists
+        for list_idx in range(len(lists)):
+            len_list = len(lists[list_idx])
+            if rel_idx < len_list:
+                break
+            rel_idx -= len_list
+        if rel_idx < 0:
+            return None, None
+        return list_idx, rel_idx
+
+    def _balance_list(self, list_idx):
+        if list_idx < 0:
+            list_idx += len(self.lists)
+        cur_list, len_self = self.lists[list_idx], len(self)
+        size_limit = self._cur_size_limit
+        if len(cur_list) > size_limit:
+            half_limit = size_limit // 2
+            while len(cur_list) > half_limit:
+                next_list_idx = list_idx + 1
+                self.lists.insert(next_list_idx, cur_list[-half_limit:])
+                del cur_list[-half_limit:]
+            return True
+        return False
+
+    def insert(self, index, item):
+        if len(self.lists) == 1:
+            self.lists[0].insert(index, item)
+            self._balance_list(0)
+        else:
+            list_idx, rel_idx = self._translate_index(index)
+            if list_idx is None:
+                raise IndexError()
+            self.lists[list_idx].insert(rel_idx, item)
+            self._balance_list(list_idx)
+        return
+
+    def append(self, item):
+        self.lists[-1].append(item)
+
+    def extend(self, iterable):
+        self.lists[-1].extend(iterable)
+
+    def pop(self, *a):
+        lists = self.lists
+        if len(lists) == 1 and not a:
+            return self.lists[0].pop()
+        index = a and a[0]
+        if index == () or index is None or index == -1:
+            ret = lists[-1].pop()
+            if len(lists) > 1 and not lists[-1]:
+                lists.pop()
+        else:
+            list_idx, rel_idx = self._translate_index(index)
+            if list_idx is None:
+                raise IndexError()
+            ret = lists[list_idx].pop(rel_idx)
+            self._balance_list(list_idx)
+        return ret
+
+    def iter_slice(self, start, stop, step=None):
+        iterable = self  # TODO: optimization opportunities abound
+        # start_list_idx, stop_list_idx = 0, len(self.lists)
+        if start is None:
+            start = 0
+        if stop is None:
+            stop = len(self)
+        if step is not None and step < 0:
+            step = -step
+            start, stop = -start, -stop - 1
+            iterable = reversed(self)
+        if start < 0:
+            start += len(self)
+            # start_list_idx, start_rel_idx = self._translate_index(start)
+        if stop < 0:
+            stop += len(self)
+            # stop_list_idx, stop_rel_idx = self._translate_index(stop)
+        return islice(iterable, start, stop, step)
+
+    def del_slice(self, start, stop, step=None):
+        if step is not None and abs(step) > 1:  # punt
+            new_list = chain(self.iter_slice(0, start, step),
+                             self.iter_slice(stop, None, step))
+            self.lists[0][:] = new_list
+            self._balance_list(0)
+            return
+        if start is None:
+            start = 0
+        if stop is None:
+            stop = len(self)
+        start_list_idx, start_rel_idx = self._translate_index(start)
+        stop_list_idx, stop_rel_idx = self._translate_index(stop)
+        if start_list_idx is None:
+            raise IndexError()
+        if stop_list_idx is None:
+            raise IndexError()
+
+        if start_list_idx == stop_list_idx:
+            del self.lists[start_list_idx][start_rel_idx:stop_rel_idx]
+        elif start_list_idx < stop_list_idx:
+            del self.lists[start_list_idx + 1:stop_list_idx]
+            del self.lists[start_list_idx][start_rel_idx:]
+            del self.lists[stop_list_idx][:stop_rel_idx]
+        else:
+            assert False, ('start list index should never translate to'
+                           ' greater than stop list index')
+
+    __delslice__ = del_slice
+
+    @classmethod
+    def from_iterable(cls, it):
+        return cls(it)
+
+    def __iter__(self):
+        return chain(*self.lists)
+
+    def __reversed__(self):
+        return chain.from_iterable(reversed(l) for l in reversed(self.lists))
+
+    def __len__(self):
+        return sum([len(l) for l in self.lists])
+
+    def __contains__(self, item):
+        for cur in self.lists:
+            if item in cur:
+                return True
+        return False
+
+    def __getitem__(self, index):
+        try:
+            start, stop, step = index.start, index.stop, index.step
+        except AttributeError:
+            index = operator.index(index)
+        else:
+            iter_slice = self.iter_slice(start, stop, step)
+            ret = self.from_iterable(iter_slice)
+            return ret
+        list_idx, rel_idx = self._translate_index(index)
+        if list_idx is None:
+            raise IndexError()
+        return self.lists[list_idx][rel_idx]
+
+    def __delitem__(self, index):
+        try:
+            start, stop, step = index.start, index.stop, index.step
+        except AttributeError:
+            index = operator.index(index)
+        else:
+            self.del_slice(start, stop, step)
+            return
+        list_idx, rel_idx = self._translate_index(index)
+        if list_idx is None:
+            raise IndexError()
+        del self.lists[list_idx][rel_idx]
+
+    def __setitem__(self, index, item):
+        try:
+            start, stop, step = index.start, index.stop, index.step
+        except AttributeError:
+            index = operator.index(index)
+        else:
+            if len(self.lists) == 1:
+                self.lists[0][index] = item
+            else:
+                tmp = list(self)
+                tmp[index] = item
+                self.lists[:] = [tmp]
+            self._balance_list(0)
+            return
+        list_idx, rel_idx = self._translate_index(index)
+        if list_idx is None:
+            raise IndexError()
+        self.lists[list_idx][rel_idx] = item
+
+    def __getslice__(self, start, stop):
+        iter_slice = self.iter_slice(start, stop, 1)
+        return self.from_iterable(iter_slice)
+
+    def __setslice__(self, start, stop, sequence):
+        if len(self.lists) == 1:
+            self.lists[0][start:stop] = sequence
+        else:
+            tmp = list(self)
+            tmp[start:stop] = sequence
+            self.lists[:] = [tmp]
+        self._balance_list(0)
+        return
+
+    def __repr__(self):
+        return '%s(%r)' % (self.__class__.__name__, list(self))
+
+    def sort(self):
+        # poor pythonist's mergesort, it's faster than sorted(self)
+        # when the lists' average length is greater than 512.
+        if len(self.lists) == 1:
+            self.lists[0].sort()
+        else:
+            for li in self.lists:
+                li.sort()
+            tmp_sorted = sorted(chain.from_iterable(self.lists))
+            del self.lists[:]
+            self.lists[0] = tmp_sorted
+            self._balance_list(0)
+
+    def reverse(self):
+        for cur in self.lists:
+            cur.reverse()
+        self.lists.reverse()
+
+    def count(self, item):
+        return sum([cur.count(item) for cur in self.lists])
+
+    def index(self, item):
+        len_accum = 0
+        for cur in self.lists:
+            try:
+                rel_idx = cur.index(item)
+                return len_accum + rel_idx
+            except ValueError:
+                len_accum += len(cur)
+        raise ValueError('%r is not in list' % (item,))
+
+
+BList = BarrelList
+
+
+class SplayList(list):
+    """Like a `splay tree`_, the SplayList facilitates moving higher
+    utility items closer to the front of the list for faster access.
+
+    .. _splay tree: https://en.wikipedia.org/wiki/Splay_tree
+    """
+
+    def shift(self, item_index, dest_index=0):
+        if item_index == dest_index:
+            return
+        item = self.pop(item_index)
+        self.insert(dest_index, item)
+
+    def swap(self, item_index, dest_index):
+        self[dest_index], self[item_index] = self[item_index], self[dest_index]