--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/env/lib/python3.7/site-packages/boltons/setutils.py	Sat May 02 07:14:21 2020 -0400
@@ -0,0 +1,939 @@
+# -*- coding: utf-8 -*-
+"""\
+
+The :class:`set` type brings the practical expressiveness of
+set theory to Python. It has a very rich API overall, but lacks a
+couple of fundamental features. For one, sets are not ordered. On top
+of this, sets are not indexable, i.e, ``my_set[8]`` will raise an
+:exc:`TypeError`. The :class:`IndexedSet` type remedies both of these
+issues without compromising on the excellent complexity
+characteristics of Python's built-in set implementation.
+"""
+
+from __future__ import print_function
+
+from bisect import bisect_left
+from itertools import chain, islice
+import operator
+
+try:
+    from collections.abc import MutableSet
+except ImportError:
+    from collections import MutableSet
+
+try:
+    from typeutils import make_sentinel
+    _MISSING = make_sentinel(var_name='_MISSING')
+except ImportError:
+    _MISSING = object()
+
+
+__all__ = ['IndexedSet', 'complement']
+
+
+_COMPACTION_FACTOR = 8
+
+# TODO: inherit from set()
+# TODO: .discard_many(), .remove_many()
+# TODO: raise exception on non-set params?
+# TODO: technically reverse operators should probably reverse the
+# order of the 'other' inputs and put self last (to try and maintain
+# insertion order)
+
+
+class IndexedSet(MutableSet):
+    """``IndexedSet`` is a :class:`collections.MutableSet` that maintains
+    insertion order and uniqueness of inserted elements. It's a hybrid
+    type, mostly like an OrderedSet, but also :class:`list`-like, in
+    that it supports indexing and slicing.
+
+    Args:
+        other (iterable): An optional iterable used to initialize the set.
+
+    >>> x = IndexedSet(list(range(4)) + list(range(8)))
+    >>> x
+    IndexedSet([0, 1, 2, 3, 4, 5, 6, 7])
+    >>> x - set(range(2))
+    IndexedSet([2, 3, 4, 5, 6, 7])
+    >>> x[-1]
+    7
+    >>> fcr = IndexedSet('freecreditreport.com')
+    >>> ''.join(fcr[:fcr.index('.')])
+    'frecditpo'
+
+    Standard set operators and interoperation with :class:`set` are
+    all supported:
+
+    >>> fcr & set('cash4gold.com')
+    IndexedSet(['c', 'd', 'o', '.', 'm'])
+
+    As you can see, the ``IndexedSet`` is almost like a ``UniqueList``,
+    retaining only one copy of a given value, in the order it was
+    first added. For the curious, the reason why IndexedSet does not
+    support setting items based on index (i.e, ``__setitem__()``),
+    consider the following dilemma::
+
+      my_indexed_set = [A, B, C, D]
+      my_indexed_set[2] = A
+
+    At this point, a set requires only one *A*, but a :class:`list` would
+    overwrite *C*. Overwriting *C* would change the length of the list,
+    meaning that ``my_indexed_set[2]`` would not be *A*, as expected with a
+    list, but rather *D*. So, no ``__setitem__()``.
+
+    Otherwise, the API strives to be as complete a union of the
+    :class:`list` and :class:`set` APIs as possible.
+    """
+    def __init__(self, other=None):
+        self.item_index_map = dict()
+        self.item_list = []
+        self.dead_indices = []
+        self._compactions = 0
+        self._c_max_size = 0
+        if other:
+            self.update(other)
+
+    # internal functions
+    @property
+    def _dead_index_count(self):
+        return len(self.item_list) - len(self.item_index_map)
+
+    def _compact(self):
+        if not self.dead_indices:
+            return
+        self._compactions += 1
+        dead_index_count = self._dead_index_count
+        items, index_map = self.item_list, self.item_index_map
+        self._c_max_size = max(self._c_max_size, len(items))
+        for i, item in enumerate(self):
+            items[i] = item
+            index_map[item] = i
+        del items[-dead_index_count:]
+        del self.dead_indices[:]
+
+    def _cull(self):
+        ded = self.dead_indices
+        if not ded:
+            return
+        items, ii_map = self.item_list, self.item_index_map
+        if not ii_map:
+            del items[:]
+            del ded[:]
+        elif len(ded) > 384:
+            self._compact()
+        elif self._dead_index_count > (len(items) / _COMPACTION_FACTOR):
+            self._compact()
+        elif items[-1] is _MISSING:  # get rid of dead right hand side
+            num_dead = 1
+            while items[-(num_dead + 1)] is _MISSING:
+                num_dead += 1
+            if ded and ded[-1][1] == len(items):
+                del ded[-1]
+            del items[-num_dead:]
+
+    def _get_real_index(self, index):
+        if index < 0:
+            index += len(self)
+        if not self.dead_indices:
+            return index
+        real_index = index
+        for d_start, d_stop in self.dead_indices:
+            if real_index < d_start:
+                break
+            real_index += d_stop - d_start
+        return real_index
+
+    def _get_apparent_index(self, index):
+        if index < 0:
+            index += len(self)
+        if not self.dead_indices:
+            return index
+        apparent_index = index
+        for d_start, d_stop in self.dead_indices:
+            if apparent_index < d_start:
+                break
+            apparent_index -= d_stop + d_start
+        return apparent_index
+
+    def _add_dead(self, start, stop=None):
+        # TODO: does not handle when the new interval subsumes
+        # multiple existing intervals
+        dints = self.dead_indices
+        if stop is None:
+            stop = start + 1
+        cand_int = [start, stop]
+        if not dints:
+            dints.append(cand_int)
+            return
+        int_idx = bisect_left(dints, cand_int)
+        dint = dints[int_idx - 1]
+        d_start, d_stop = dint
+        if start <= d_start <= stop:
+            dint[0] = start
+        elif start <= d_stop <= stop:
+            dint[1] = stop
+        else:
+            dints.insert(int_idx, cand_int)
+        return
+
+    # common operations (shared by set and list)
+    def __len__(self):
+        return len(self.item_index_map)
+
+    def __contains__(self, item):
+        return item in self.item_index_map
+
+    def __iter__(self):
+        return (item for item in self.item_list if item is not _MISSING)
+
+    def __reversed__(self):
+        item_list = self.item_list
+        return (item for item in reversed(item_list) if item is not _MISSING)
+
+    def __repr__(self):
+        return '%s(%r)' % (self.__class__.__name__, list(self))
+
+    def __eq__(self, other):
+        if isinstance(other, IndexedSet):
+            return len(self) == len(other) and list(self) == list(other)
+        return set(self) == set(other)
+
+    @classmethod
+    def from_iterable(cls, it):
+        "from_iterable(it) -> create a set from an iterable"
+        return cls(it)
+
+    # set operations
+    def add(self, item):
+        "add(item) -> add item to the set"
+        if item not in self.item_index_map:
+            self.item_index_map[item] = len(self.item_list)
+            self.item_list.append(item)
+
+    def remove(self, item):
+        "remove(item) -> remove item from the set, raises if not present"
+        try:
+            didx = self.item_index_map.pop(item)
+        except KeyError:
+            raise KeyError(item)
+        self.item_list[didx] = _MISSING
+        self._add_dead(didx)
+        self._cull()
+
+    def discard(self, item):
+        "discard(item) -> discard item from the set (does not raise)"
+        try:
+            self.remove(item)
+        except KeyError:
+            pass
+
+    def clear(self):
+        "clear() -> empty the set"
+        del self.item_list[:]
+        del self.dead_indices[:]
+        self.item_index_map.clear()
+
+    def isdisjoint(self, other):
+        "isdisjoint(other) -> return True if no overlap with other"
+        iim = self.item_index_map
+        for k in other:
+            if k in iim:
+                return False
+        return True
+
+    def issubset(self, other):
+        "issubset(other) -> return True if other contains this set"
+        if len(other) < len(self):
+            return False
+        for k in self.item_index_map:
+            if k not in other:
+                return False
+        return True
+
+    def issuperset(self, other):
+        "issuperset(other) -> return True if set contains other"
+        if len(other) > len(self):
+            return False
+        iim = self.item_index_map
+        for k in other:
+            if k not in iim:
+                return False
+        return True
+
+    def union(self, *others):
+        "union(*others) -> return a new set containing this set and others"
+        return self.from_iterable(chain(self, *others))
+
+    def iter_intersection(self, *others):
+        "iter_intersection(*others) -> iterate over elements also in others"
+        for k in self:
+            for other in others:
+                if k not in other:
+                    break
+            else:
+                yield k
+        return
+
+    def intersection(self, *others):
+        "intersection(*others) -> get a set with overlap of this and others"
+        if len(others) == 1:
+            other = others[0]
+            return self.from_iterable(k for k in self if k in other)
+        return self.from_iterable(self.iter_intersection(*others))
+
+    def iter_difference(self, *others):
+        "iter_difference(*others) -> iterate over elements not in others"
+        for k in self:
+            for other in others:
+                if k in other:
+                    break
+            else:
+                yield k
+        return
+
+    def difference(self, *others):
+        "difference(*others) -> get a new set with elements not in others"
+        if len(others) == 1:
+            other = others[0]
+            return self.from_iterable(k for k in self if k not in other)
+        return self.from_iterable(self.iter_difference(*others))
+
+    def symmetric_difference(self, *others):
+        "symmetric_difference(*others) -> XOR set of this and others"
+        ret = self.union(*others)
+        return ret.difference(self.intersection(*others))
+
+    __or__  = __ror__  = union
+    __and__ = __rand__ = intersection
+    __sub__ = __rsub__ = difference
+    __xor__ = __rxor__ = symmetric_difference
+
+    # in-place set operations
+    def update(self, *others):
+        "update(*others) -> add values from one or more iterables"
+        if not others:
+            return  # raise?
+        elif len(others) == 1:
+            other = others[0]
+        else:
+            other = chain(others)
+        for o in other:
+            self.add(o)
+
+    def intersection_update(self, *others):
+        "intersection_update(*others) -> discard self.difference(*others)"
+        for val in self.difference(*others):
+            self.discard(val)
+
+    def difference_update(self, *others):
+        "difference_update(*others) -> discard self.intersection(*others)"
+        if self in others:
+            self.clear()
+        for val in self.intersection(*others):
+            self.discard(val)
+
+    def symmetric_difference_update(self, other):  # note singular 'other'
+        "symmetric_difference_update(other) -> in-place XOR with other"
+        if self is other:
+            self.clear()
+        for val in other:
+            if val in self:
+                self.discard(val)
+            else:
+                self.add(val)
+
+    def __ior__(self, *others):
+        self.update(*others)
+        return self
+
+    def __iand__(self, *others):
+        self.intersection_update(*others)
+        return self
+
+    def __isub__(self, *others):
+        self.difference_update(*others)
+        return self
+
+    def __ixor__(self, *others):
+        self.symmetric_difference_update(*others)
+        return self
+
+    def iter_slice(self, start, stop, step=None):
+        "iterate over a slice of the set"
+        iterable = self
+        if start is not None:
+            start = self._get_real_index(start)
+        if stop is not None:
+            stop = self._get_real_index(stop)
+        if step is not None and step < 0:
+            step = -step
+            iterable = reversed(self)
+        return islice(iterable, start, stop, step)
+
+    # list operations
+    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)
+            return self.from_iterable(iter_slice)
+        if index < 0:
+            index += len(self)
+        real_index = self._get_real_index(index)
+        try:
+            ret = self.item_list[real_index]
+        except IndexError:
+            raise IndexError('IndexedSet index out of range')
+        return ret
+
+    def pop(self, index=None):
+        "pop(index) -> remove the item at a given index (-1 by default)"
+        item_index_map = self.item_index_map
+        len_self = len(item_index_map)
+        if index is None or index == -1 or index == len_self - 1:
+            ret = self.item_list.pop()
+            del item_index_map[ret]
+        else:
+            real_index = self._get_real_index(index)
+            ret = self.item_list[real_index]
+            self.item_list[real_index] = _MISSING
+            del item_index_map[ret]
+            self._add_dead(real_index)
+        self._cull()
+        return ret
+
+    def count(self, val):
+        "count(val) -> count number of instances of value (0 or 1)"
+        if val in self.item_index_map:
+            return 1
+        return 0
+
+    def reverse(self):
+        "reverse() -> reverse the contents of the set in-place"
+        reversed_list = list(reversed(self))
+        self.item_list[:] = reversed_list
+        for i, item in enumerate(self.item_list):
+            self.item_index_map[item] = i
+        del self.dead_indices[:]
+
+    def sort(self, **kwargs):
+        "sort() -> sort the contents of the set in-place"
+        sorted_list = sorted(self, **kwargs)
+        if sorted_list == self.item_list:
+            return
+        self.item_list[:] = sorted_list
+        for i, item in enumerate(self.item_list):
+            self.item_index_map[item] = i
+        del self.dead_indices[:]
+
+    def index(self, val):
+        "index(val) -> get the index of a value, raises if not present"
+        try:
+            return self._get_apparent_index(self.item_index_map[val])
+        except KeyError:
+            cn = self.__class__.__name__
+            raise ValueError('%r is not in %s' % (val, cn))
+
+
+def complement(wrapped):
+    """Given a :class:`set`, convert it to a **complement set**.
+
+    Whereas a :class:`set` keeps track of what it contains, a
+    `complement set
+    <https://en.wikipedia.org/wiki/Complement_(set_theory)>`_ keeps
+    track of what it does *not* contain. For example, look what
+    happens when we intersect a normal set with a complement set::
+
+    >>> list(set(range(5)) & complement(set([2, 3])))
+    [0, 1, 4]
+
+    We get the everything in the left that wasn't in the right,
+    because intersecting with a complement is the same as subtracting
+    a normal set.
+
+    Args:
+        wrapped (set): A set or any other iterable which should be
+           turned into a complement set.
+
+    All set methods and operators are supported by complement sets,
+    between other :func:`complement`-wrapped sets and/or regular
+    :class:`set` objects.
+
+    Because a complement set only tracks what elements are *not* in
+    the set, functionality based on set contents is unavailable:
+    :func:`len`, :func:`iter` (and for loops), and ``.pop()``. But a
+    complement set can always be turned back into a regular set by
+    complementing it again:
+
+    >>> s = set(range(5))
+    >>> complement(complement(s)) == s
+    True
+
+    .. note::
+
+       An empty complement set corresponds to the concept of a
+       `universal set <https://en.wikipedia.org/wiki/Universal_set>`_
+       from mathematics.
+
+    Complement sets by example
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+    Many uses of sets can be expressed more simply by using a
+    complement. Rather than trying to work out in your head the proper
+    way to invert an expression, you can just throw a complement on
+    the set. Consider this example of a name filter::
+
+        >>> class NamesFilter(object):
+        ...    def __init__(self, allowed):
+        ...        self._allowed = allowed
+        ...
+        ...    def filter(self, names):
+        ...        return [name for name in names if name in self._allowed]
+        >>> NamesFilter(set(['alice', 'bob'])).filter(['alice', 'bob', 'carol'])
+        ['alice', 'bob']
+
+    What if we want to just express "let all the names through"?
+
+    We could try to enumerate all of the expected names::
+
+       ``NamesFilter({'alice', 'bob', 'carol'})``
+
+    But this is very brittle -- what if at some point over this
+    object is changed to filter ``['alice', 'bob', 'carol', 'dan']``?
+
+    Even worse, what about the poor programmer who next works
+    on this piece of code?  They cannot tell whether the purpose
+    of the large allowed set was "allow everything", or if 'dan'
+    was excluded for some subtle reason.
+
+    A complement set lets the programmer intention be expressed
+    succinctly and directly::
+
+       NamesFilter(complement(set()))
+
+    Not only is this code short and robust, it is easy to understand
+    the intention.
+
+    """
+    if type(wrapped) is _ComplementSet:
+        return wrapped.complemented()
+    if type(wrapped) is frozenset:
+        return _ComplementSet(excluded=wrapped)
+    return _ComplementSet(excluded=set(wrapped))
+
+
+def _norm_args_typeerror(other):
+    '''normalize args and raise type-error if there is a problem'''
+    if type(other) in (set, frozenset):
+        inc, exc = other, None
+    elif type(other) is _ComplementSet:
+        inc, exc = other._included, other._excluded
+    else:
+        raise TypeError('argument must be another set or complement(set)')
+    return inc, exc
+
+
+def _norm_args_notimplemented(other):
+    '''normalize args and return NotImplemented (for overloaded operators)'''
+    if type(other) in (set, frozenset):
+        inc, exc = other, None
+    elif type(other) is _ComplementSet:
+        inc, exc = other._included, other._excluded
+    else:
+        return NotImplemented, None
+    return inc, exc
+
+
+class _ComplementSet(object):
+    """
+    helper class for complement() that implements the set methods
+    """
+    __slots__ = ('_included', '_excluded')
+
+    def __init__(self, included=None, excluded=None):
+        if included is None:
+            assert type(excluded) in (set, frozenset)
+        elif excluded is None:
+            assert type(included) in (set, frozenset)
+        else:
+            raise ValueError('one of included or excluded must be a set')
+        self._included, self._excluded = included, excluded
+
+    def __repr__(self):
+        if self._included is None:
+            return 'complement({0})'.format(repr(self._excluded))
+        return 'complement(complement({0}))'.format(repr(self._included))
+
+    def complemented(self):
+        '''return a complement of the current set'''
+        if type(self._included) is frozenset or type(self._excluded) is frozenset:
+            return _ComplementSet(included=self._excluded, excluded=self._included)
+        return _ComplementSet(
+            included=None if self._excluded is None else set(self._excluded),
+            excluded=None if self._included is None else set(self._included))
+
+    __invert__ = complemented
+
+    def complement(self):
+        '''convert the current set to its complement in-place'''
+        self._included, self._excluded = self._excluded, self._included
+
+    def __contains__(self, item):
+        if self._included is None:
+            return not item in self._excluded
+        return item in self._included
+
+    def add(self, item):
+        if self._included is None:
+            if item in self._excluded:
+                self._excluded.remove(item)
+        else:
+            self._included.add(item)
+
+    def remove(self, item):
+        if self._included is None:
+            self._excluded.add(item)
+        else:
+            self._included.remove(item)
+
+    def pop(self):
+        if self._included is None:
+            raise NotImplementedError  # self.missing.add(random.choice(gc.objects()))
+        return self._included.pop()
+
+    def intersection(self, other):
+        try:
+            return self & other
+        except NotImplementedError:
+            raise TypeError('argument must be another set or complement(set)')
+
+    def __and__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                return _ComplementSet(included=inc - self._excluded)
+            else:  # - -
+                return _ComplementSet(excluded=self._excluded.union(other._excluded))
+        else:
+            if inc is None:  # + -
+                return _ComplementSet(included=exc - self._included)
+            else:  # + +
+                return _ComplementSet(included=self._included.intersection(inc))
+
+    __rand__ = __and__
+
+    def __iand__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                self._excluded = inc - self._excluded  # TODO: do this in place?
+            else:  # - -
+                self._excluded |= exc
+        else:
+            if inc is None:  # + -
+                self._included -= exc
+                self._included, self._excluded = None, self._included
+            else:  # + +
+                self._included &= inc
+        return self
+
+    def union(self, other):
+        try:
+            return self | other
+        except NotImplementedError:
+            raise TypeError('argument must be another set or complement(set)')
+
+    def __or__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                return _ComplementSet(excluded=self._excluded - inc)
+            else:  # - -
+                return _ComplementSet(excluded=self._excluded.intersection(exc))
+        else:
+            if inc is None:  # + -
+                return _ComplementSet(excluded=exc - self._included)
+            else:  # + +
+                return _ComplementSet(included=self._included.union(inc))
+
+    __ror__ = __or__
+
+    def __ior__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                self._excluded -= inc
+            else:  # - -
+                self._excluded &= exc
+        else:
+            if inc is None:  # + -
+                self._included, self._excluded = None, exc - self._included   # TODO: do this in place?
+            else:  # + +
+                self._included |= inc
+        return self
+
+    def update(self, items):
+        if type(items) in (set, frozenset):
+            inc, exc = items, None
+        elif type(items) is _ComplementSet:
+            inc, exc = items._included, items._excluded
+        else:
+            inc, exc = frozenset(items), None
+        if self._included is None:
+            if exc is None:  # - +
+                self._excluded &= inc
+            else:  # - -
+                self._excluded.discard(exc)
+        else:
+            if inc is None:  # + -
+                self._included &= exc
+                self._included, self._excluded = None, self._excluded
+            else:  # + +
+                self._included.update(inc)
+
+    def discard(self, items):
+        if type(items) in (set, frozenset):
+            inc, exc = items, None
+        elif type(items) is _ComplementSet:
+            inc, exc = items._included, items._excluded
+        else:
+            inc, exc = frozenset(items), None
+        if self._included is None:
+            if exc is None:  # - +
+                self._excluded.update(inc)
+            else:  # - -
+                self._included, self._excluded = exc - self._excluded, None
+        else:
+            if inc is None:  # + -
+                self._included &= exc
+            else:  # + +
+                self._included.discard(inc)
+
+    def symmetric_difference(self, other):
+        try:
+            return self ^ other
+        except NotImplementedError:
+            raise TypeError('argument must be another set or complement(set)')
+
+    def __xor__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                return _ComplementSet(excluded=self._excluded - inc)
+            else:  # - -
+                return _ComplementSet(included=self._excluded.symmetric_difference(exc))
+        else:
+            if inc is None:  # + -
+                return _ComplementSet(excluded=exc - self._included)
+            else:  # + +
+                return _ComplementSet(included=self._included.symmetric_difference(inc))
+
+    __rxor__ = __xor__
+
+    def symmetric_difference_update(self, other):
+        inc, exc = _norm_args_typeerror(other)
+        if self._included is None:
+            if exc is None:  # - +
+                self._excluded |= inc
+            else:  # - -
+                self._excluded.symmetric_difference_update(exc)
+                self._included, self._excluded = self._excluded, None
+        else:
+            if inc is None:  # + -
+                self._included |= exc
+                self._included, self._excluded = None, self._included
+            else:  # + +
+                self._included.symmetric_difference_update(inc)
+
+    def isdisjoint(self, other):
+        inc, exc = _norm_args_typeerror(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                return inc.issubset(self._excluded)
+            else:  # - -
+                return False
+        else:
+            if inc is None:  # + -
+                return self._included.issubset(exc)
+            else:  # + +
+                return self._included.isdisjoint(inc)
+
+    def issubset(self, other):
+        '''everything missing from other is also missing from self'''
+        try:
+            return self <= other
+        except NotImplementedError:
+            raise TypeError('argument must be another set or complement(set)')
+
+    def __le__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                return False
+            else:  # - -
+                return self._excluded.issupserset(exc)
+        else:
+            if inc is None:  # + -
+                return self._included.isdisjoint(exc)
+            else:  # + +
+                return self._included.issubset(inc)
+
+    def __lt__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                return False
+            else:  # - -
+                return self._excluded > exc
+        else:
+            if inc is None:  # + -
+                return self._included.isdisjoint(exc)
+            else:  # + +
+                return self._included < inc
+
+    def issuperset(self, other):
+        '''everything missing from self is also missing from super'''
+        try:
+            return self >= other
+        except NotImplementedError:
+            raise TypeError('argument must be another set or complement(set)')
+
+    def __ge__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                return not self._excluded.intersection(inc)
+            else:  # - -
+                return self._excluded.issubset(exc)
+        else:
+            if inc is None:  # + -
+                return False
+            else:  # + +
+                return self._included.issupserset(inc)
+
+    def __gt__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                return not self._excluded.intersection(inc)
+            else:  # - -
+                return self._excluded < exc
+        else:
+            if inc is None:  # + -
+                return False
+            else:  # + +
+                return self._included > inc
+
+    def difference(self, other):
+        try:
+            return self - other
+        except NotImplementedError:
+            raise TypeError('argument must be another set or complement(set)')
+
+    def __sub__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                return _ComplementSet(excluded=self._excluded | inc)
+            else:  # - -
+                return _ComplementSet(included=exc - self._excluded)
+        else:
+            if inc is None:  # + -
+                return _ComplementSet(included=self._included & exc)
+            else:  # + +
+                return _ComplementSet(included=self._included.difference(inc))
+
+    def __rsub__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        # rsub, so the expression being evaluated is "other - self"
+        if self._included is None:
+            if exc is None:  # - +
+                return _ComplementSet(included=inc & self._excluded)
+            else:  # - -
+                return _ComplementSet(included=self._excluded - exc)
+        else:
+            if inc is None:  # + -
+                return _ComplementSet(excluded=exc | self._included)
+            else:  # + +
+                return _ComplementSet(included=inc.difference(self._included))
+
+    def difference_update(self, other):
+        try:
+            self -= other
+        except NotImplementedError:
+            raise TypeError('argument must be another set or complement(set)')
+
+    def __isub__(self, other):
+        inc, exc = _norm_args_notimplemented(other)
+        if inc is NotImplemented:
+            return NotImplemented
+        if self._included is None:
+            if exc is None:  # - +
+                self._excluded |= inc
+            else:  # - -
+                self._included, self._excluded = exc - self._excluded, None
+        else:
+            if inc is None:  # + -
+                self._included &= exc
+            else:  # + +
+                self._included.difference_update(inc)
+        return self
+
+    def __eq__(self, other):
+        return (
+            type(self) is type(other)
+            and self._included == other._included
+            and self._excluded == other._excluded) or (
+            type(other) in (set, frozenset) and self._included == other)
+
+    def __hash__(self):
+        return hash(self._included) ^ hash(self._excluded)
+
+    def __len__(self):
+        if self._included is not None:
+            return len(self._included)
+        raise NotImplementedError('complemented sets have undefined length')
+
+    def __iter__(self):
+        if self._included is not None:
+            return iter(self._included)
+        raise NotImplementedError('complemented sets have undefined contents')
+
+    def __bool__(self):
+        if self._included is not None:
+            return bool(self._included)
+        return True
+
+    __nonzero__ = __bool__  # py2 compat