FM / python3.6

/snap/core18/2999/usr/lib/python3.6

Name	Size	Mode	Actions
asyncio/	-	0755	rm
collections/	-	0755	rm
concurrent/	-	0755	rm
ctypes/	-	0755	rm
curses/	-	0755	rm
dbm/	-	0755	rm
distutils/	-	0755	rm
email/	-	0755	rm
encodings/	-	0755	rm
html/	-	0755	rm
http/	-	0755	rm
importlib/	-	0755	rm
json/	-	0755	rm
lib-dynload/	-	0755	rm
lib2to3/	-	0755	rm
logging/	-	0755	rm
multiprocessing/	-	0755	rm
pydoc_data/	-	0755	rm
sqlite3/	-	0755	rm
test/	-	0755	rm
unittest/	-	0755	rm
urllib/	-	0755	rm
venv/	-	0755	rm
wsgiref/	-	0755	rm
xml/	-	0755	rm
xmlrpc/	-	0755	rm
__pycache__/	-	0755	rm
abc.py	8727	0644	edit dl rm
aifc.py	32454	0644	edit dl rm
antigravity.py	477	0644	edit dl rm
argparse.py	90568	0644	edit dl rm
ast.py	12166	0644	edit dl rm
asynchat.py	11328	0644	edit dl rm
asyncore.py	20159	0644	edit dl rm
base64.py	20378	0755	edit dl rm
bdb.py	23556	0644	edit dl rm
binhex.py	13954	0644	edit dl rm
bisect.py	2595	0644	edit dl rm
bz2.py	12478	0644	edit dl rm
calendar.py	23213	0644	edit dl rm
cgi.py	36791	0755	edit dl rm
cgitb.py	12018	0644	edit dl rm
chunk.py	5425	0644	edit dl rm
cmd.py	14860	0644	edit dl rm
code.py	10614	0644	edit dl rm
codecs.py	36276	0644	edit dl rm
codeop.py	5994	0644	edit dl rm
colorsys.py	4064	0644	edit dl rm
compileall.py	12125	0644	edit dl rm
configparser.py	53592	0644	edit dl rm
contextlib.py	13162	0644	edit dl rm
copy.py	8815	0644	edit dl rm
copyreg.py	7007	0644	edit dl rm
cProfile.py	5370	0755	edit dl rm
crypt.py	1864	0644	edit dl rm
csv.py	16180	0644	edit dl rm
datetime.py	82034	0644	edit dl rm
decimal.py	320	0644	edit dl rm
difflib.py	84377	0644	edit dl rm
dis.py	18132	0644	edit dl rm
doctest.py	104391	0644	edit dl rm
dummy_threading.py	2815	0644	edit dl rm
enum.py	33606	0644	edit dl rm
filecmp.py	9830	0644	edit dl rm
fileinput.py	14471	0644	edit dl rm
fnmatch.py	3166	0644	edit dl rm
formatter.py	15143	0644	edit dl rm
fractions.py	23639	0644	edit dl rm
ftplib.py	35617	0644	edit dl rm
functools.py	31346	0644	edit dl rm
genericpath.py	4756	0644	edit dl rm
getopt.py	7489	0644	edit dl rm
getpass.py	5994	0644	edit dl rm
gettext.py	21957	0644	edit dl rm
glob.py	5638	0644	edit dl rm
gzip.py	20334	0644	edit dl rm
hashlib.py	9533	0644	edit dl rm
heapq.py	22929	0644	edit dl rm
hmac.py	5057	0644	edit dl rm
imaplib.py	53295	0644	edit dl rm
imghdr.py	3795	0644	edit dl rm
imp.py	10669	0644	edit dl rm
inspect.py	116958	0644	edit dl rm
io.py	3517	0644	edit dl rm
ipaddress.py	74563	0644	edit dl rm
keyword.py	2209	0755	edit dl rm
LICENSE.txt	12769	0644	edit dl rm
linecache.py	5312	0644	edit dl rm
locale.py	77304	0644	edit dl rm
lzma.py	12983	0644	edit dl rm
macpath.py	5971	0644	edit dl rm
macurl2path.py	2732	0644	edit dl rm
mailbox.py	78624	0644	edit dl rm
mailcap.py	9067	0644	edit dl rm
mimetypes.py	21042	0644	edit dl rm
modulefinder.py	23027	0644	edit dl rm
netrc.py	5684	0644	edit dl rm
nntplib.py	43078	0644	edit dl rm
ntpath.py	21174	0644	edit dl rm
nturl2path.py	2444	0644	edit dl rm
numbers.py	10243	0644	edit dl rm
opcode.py	5822	0644	edit dl rm
operator.py	10863	0644	edit dl rm
optparse.py	60371	0644	edit dl rm
os.py	37526	0644	edit dl rm
pathlib.py	48982	0644	edit dl rm
pdb.py	61310	0755	edit dl rm
pickle.py	55691	0644	edit dl rm
pickletools.py	91775	0644	edit dl rm
pipes.py	8916	0644	edit dl rm
pkgutil.py	21315	0644	edit dl rm
platform.py	48198	0755	edit dl rm
plistlib.py	32787	0644	edit dl rm
poplib.py	14964	0644	edit dl rm
posixpath.py	15645	0644	edit dl rm
pprint.py	20860	0644	edit dl rm
profile.py	22019	0755	edit dl rm
pstats.py	26564	0644	edit dl rm
pty.py	4763	0644	edit dl rm
pyclbr.py	13558	0644	edit dl rm
pydoc.py	103818	0755	edit dl rm
py_compile.py	7181	0644	edit dl rm
queue.py	8780	0644	edit dl rm
quopri.py	7252	0755	edit dl rm
random.py	27442	0644	edit dl rm
re.py	15552	0644	edit dl rm
reprlib.py	5336	0644	edit dl rm
rlcompleter.py	7097	0644	edit dl rm
runpy.py	11959	0644	edit dl rm
sched.py	6511	0644	edit dl rm
secrets.py	2038	0644	edit dl rm
selectors.py	19438	0644	edit dl rm
shelve.py	8515	0644	edit dl rm
shlex.py	12956	0644	edit dl rm
shutil.py	40540	0644	edit dl rm
signal.py	2123	0644	edit dl rm
site.py	21766	0644	edit dl rm
sitecustomize.py	-	0	edit dl rm
smtpd.py	34709	0755	edit dl rm
smtplib.py	44208	0755	edit dl rm
sndhdr.py	7088	0644	edit dl rm
socket.py	27443	0644	edit dl rm
socketserver.py	27010	0644	edit dl rm
sre_compile.py	19338	0644	edit dl rm
sre_constants.py	6821	0644	edit dl rm
sre_parse.py	36536	0644	edit dl rm
ssl.py	46400	0644	edit dl rm
stat.py	5038	0644	edit dl rm
statistics.py	20673	0644	edit dl rm
string.py	11795	0644	edit dl rm
stringprep.py	12917	0644	edit dl rm
struct.py	257	0644	edit dl rm
subprocess.py	62339	0644	edit dl rm
sunau.py	18095	0644	edit dl rm
symbol.py	2109	0755	edit dl rm
symtable.py	7277	0644	edit dl rm
sysconfig.py	25057	0644	edit dl rm
tabnanny.py	11401	0755	edit dl rm
tarfile.py	94969	0755	edit dl rm
telnetlib.py	23136	0644	edit dl rm
tempfile.py	31867	0644	edit dl rm
textwrap.py	19558	0644	edit dl rm
this.py	1003	0644	edit dl rm
threading.py	49029	0644	edit dl rm
timeit.py	13332	0755	edit dl rm
token.py	3075	0644	edit dl rm
tokenize.py	29496	0644	edit dl rm
trace.py	28723	0755	edit dl rm
traceback.py	23458	0644	edit dl rm
tracemalloc.py	16658	0644	edit dl rm
tty.py	879	0644	edit dl rm
turtle.py	143620	0644	edit dl rm
types.py	8870	0644	edit dl rm
typing.py	80274	0644	edit dl rm
uu.py	6753	0755	edit dl rm
uuid.py	23971	0644	edit dl rm
warnings.py	18488	0644	edit dl rm
wave.py	17709	0644	edit dl rm
weakref.py	20466	0644	edit dl rm
webbrowser.py	21757	0755	edit dl rm
xdrlib.py	5913	0644	edit dl rm
zipapp.py	7157	0644	edit dl rm
zipfile.py	78184	0644	edit dl rm
_bootlocale.py	1301	0644	edit dl rm
_collections_abc.py	26392	0644	edit dl rm
_compat_pickle.py	8749	0644	edit dl rm
_compression.py	5340	0644	edit dl rm
_dummy_thread.py	5118	0644	edit dl rm
_markupbase.py	14598	0644	edit dl rm
_osx_support.py	19119	0644	edit dl rm
_pydecimal.py	230228	0644	edit dl rm
_pyio.py	88097	0644	edit dl rm
_sitebuiltins.py	3115	0644	edit dl rm
_strptime.py	24747	0644	edit dl rm
_sysconfigdata_m_linux_x86_64-linux-gnu.py	22325	0644	edit dl rm
_threading_local.py	7214	0644	edit dl rm
_weakrefset.py	5705	0644	edit dl rm
__future__.py	4841	0644	edit dl rm
__phello__.foo.py	64	0644	edit dl rm

Edit: /snap/core18/2999/usr/lib/python3.6/_collections_abc.py (26392B)

# Copyright 2007 Google, Inc. All Rights Reserved.
# Licensed to PSF under a Contributor Agreement.

"""Abstract Base Classes (ABCs) for collections, according to PEP 3119.

Unit tests are in test_collections.
"""

from abc import ABCMeta, abstractmethod
import sys

__all__ = ["Awaitable", "Coroutine",
           "AsyncIterable", "AsyncIterator", "AsyncGenerator",
           "Hashable", "Iterable", "Iterator", "Generator", "Reversible",
           "Sized", "Container", "Callable", "Collection",
           "Set", "MutableSet",
           "Mapping", "MutableMapping",
           "MappingView", "KeysView", "ItemsView", "ValuesView",
           "Sequence", "MutableSequence",
           "ByteString",
           ]

# This module has been renamed from collections.abc to _collections_abc to
# speed up interpreter startup. Some of the types such as MutableMapping are
# required early but collections module imports a lot of other modules.
# See issue #19218
__name__ = "collections.abc"

# Private list of types that we want to register with the various ABCs
# so that they will pass tests like:
#       it = iter(somebytearray)
#       assert isinstance(it, Iterable)
# Note:  in other implementations, these types might not be distinct
# and they may have their own implementation specific types that
# are not included on this list.
bytes_iterator = type(iter(b''))
bytearray_iterator = type(iter(bytearray()))
#callable_iterator = ???
dict_keyiterator = type(iter({}.keys()))
dict_valueiterator = type(iter({}.values()))
dict_itemiterator = type(iter({}.items()))
list_iterator = type(iter([]))
list_reverseiterator = type(iter(reversed([])))
range_iterator = type(iter(range(0)))
longrange_iterator = type(iter(range(1 << 1000)))
set_iterator = type(iter(set()))
str_iterator = type(iter(""))
tuple_iterator = type(iter(()))
zip_iterator = type(iter(zip()))
## views ##
dict_keys = type({}.keys())
dict_values = type({}.values())
dict_items = type({}.items())
## misc ##
mappingproxy = type(type.__dict__)
generator = type((lambda: (yield))())
## coroutine ##
async def _coro(): pass
_coro = _coro()
coroutine = type(_coro)
_coro.close()  # Prevent ResourceWarning
del _coro
## asynchronous generator ##
async def _ag(): yield
_ag = _ag()
async_generator = type(_ag)
del _ag

### ONE-TRICK PONIES ###

def _check_methods(C, *methods):
    mro = C.__mro__
    for method in methods:
        for B in mro:
            if method in B.__dict__:
                if B.__dict__[method] is None:
                    return NotImplemented
                break
        else:
            return NotImplemented
    return True

class Hashable(metaclass=ABCMeta):

__slots__ = ()

@abstractmethod
    def __hash__(self):
        return 0

@classmethod
    def __subclasshook__(cls, C):
        if cls is Hashable:
            return _check_methods(C, "__hash__")
        return NotImplemented

class Awaitable(metaclass=ABCMeta):

__slots__ = ()

@abstractmethod
    def __await__(self):
        yield

@classmethod
    def __subclasshook__(cls, C):
        if cls is Awaitable:
            return _check_methods(C, "__await__")
        return NotImplemented

class Coroutine(Awaitable):

__slots__ = ()

@abstractmethod
    def send(self, value):
        """Send a value into the coroutine.
        Return next yielded value or raise StopIteration.
        """
        raise StopIteration

@abstractmethod
    def throw(self, typ, val=None, tb=None):
        """Raise an exception in the coroutine.
        Return next yielded value or raise StopIteration.
        """
        if val is None:
            if tb is None:
                raise typ
            val = typ()
        if tb is not None:
            val = val.with_traceback(tb)
        raise val

def close(self):
        """Raise GeneratorExit inside coroutine.
        """
        try:
            self.throw(GeneratorExit)
        except (GeneratorExit, StopIteration):
            pass
        else:
            raise RuntimeError("coroutine ignored GeneratorExit")

@classmethod
    def __subclasshook__(cls, C):
        if cls is Coroutine:
            return _check_methods(C, '__await__', 'send', 'throw', 'close')
        return NotImplemented

Coroutine.register(coroutine)

class AsyncIterable(metaclass=ABCMeta):

__slots__ = ()

@abstractmethod
    def __aiter__(self):
        return AsyncIterator()

@classmethod
    def __subclasshook__(cls, C):
        if cls is AsyncIterable:
            return _check_methods(C, "__aiter__")
        return NotImplemented

class AsyncIterator(AsyncIterable):

__slots__ = ()

@abstractmethod
    async def __anext__(self):
        """Return the next item or raise StopAsyncIteration when exhausted."""
        raise StopAsyncIteration

def __aiter__(self):
        return self

@classmethod
    def __subclasshook__(cls, C):
        if cls is AsyncIterator:
            return _check_methods(C, "__anext__", "__aiter__")
        return NotImplemented

class AsyncGenerator(AsyncIterator):

__slots__ = ()

async def __anext__(self):
        """Return the next item from the asynchronous generator.
        When exhausted, raise StopAsyncIteration.
        """
        return await self.asend(None)

@abstractmethod
    async def asend(self, value):
        """Send a value into the asynchronous generator.
        Return next yielded value or raise StopAsyncIteration.
        """
        raise StopAsyncIteration

@abstractmethod
    async def athrow(self, typ, val=None, tb=None):
        """Raise an exception in the asynchronous generator.
        Return next yielded value or raise StopAsyncIteration.
        """
        if val is None:
            if tb is None:
                raise typ
            val = typ()
        if tb is not None:
            val = val.with_traceback(tb)
        raise val

async def aclose(self):
        """Raise GeneratorExit inside coroutine.
        """
        try:
            await self.athrow(GeneratorExit)
        except (GeneratorExit, StopAsyncIteration):
            pass
        else:
            raise RuntimeError("asynchronous generator ignored GeneratorExit")

@classmethod
    def __subclasshook__(cls, C):
        if cls is AsyncGenerator:
            return _check_methods(C, '__aiter__', '__anext__',
                                  'asend', 'athrow', 'aclose')
        return NotImplemented

AsyncGenerator.register(async_generator)

class Iterable(metaclass=ABCMeta):

__slots__ = ()

@abstractmethod
    def __iter__(self):
        while False:
            yield None

@classmethod
    def __subclasshook__(cls, C):
        if cls is Iterable:
            return _check_methods(C, "__iter__")
        return NotImplemented

class Iterator(Iterable):

__slots__ = ()

@abstractmethod
    def __next__(self):
        'Return the next item from the iterator. When exhausted, raise StopIteration'
        raise StopIteration

def __iter__(self):
        return self

@classmethod
    def __subclasshook__(cls, C):
        if cls is Iterator:
            return _check_methods(C, '__iter__', '__next__')
        return NotImplemented

Iterator.register(bytes_iterator)
Iterator.register(bytearray_iterator)
#Iterator.register(callable_iterator)
Iterator.register(dict_keyiterator)
Iterator.register(dict_valueiterator)
Iterator.register(dict_itemiterator)
Iterator.register(list_iterator)
Iterator.register(list_reverseiterator)
Iterator.register(range_iterator)
Iterator.register(longrange_iterator)
Iterator.register(set_iterator)
Iterator.register(str_iterator)
Iterator.register(tuple_iterator)
Iterator.register(zip_iterator)

class Reversible(Iterable):

__slots__ = ()

@abstractmethod
    def __reversed__(self):
        while False:
            yield None

@classmethod
    def __subclasshook__(cls, C):
        if cls is Reversible:
            return _check_methods(C, "__reversed__", "__iter__")
        return NotImplemented

class Generator(Iterator):

__slots__ = ()

def __next__(self):
        """Return the next item from the generator.
        When exhausted, raise StopIteration.
        """
        return self.send(None)

@abstractmethod
    def send(self, value):
        """Send a value into the generator.
        Return next yielded value or raise StopIteration.
        """
        raise StopIteration

@abstractmethod
    def throw(self, typ, val=None, tb=None):
        """Raise an exception in the generator.
        Return next yielded value or raise StopIteration.
        """
        if val is None:
            if tb is None:
                raise typ
            val = typ()
        if tb is not None:
            val = val.with_traceback(tb)
        raise val

def close(self):
        """Raise GeneratorExit inside generator.
        """
        try:
            self.throw(GeneratorExit)
        except (GeneratorExit, StopIteration):
            pass
        else:
            raise RuntimeError("generator ignored GeneratorExit")

@classmethod
    def __subclasshook__(cls, C):
        if cls is Generator:
            return _check_methods(C, '__iter__', '__next__',
                                  'send', 'throw', 'close')
        return NotImplemented

Generator.register(generator)

class Sized(metaclass=ABCMeta):

__slots__ = ()

@abstractmethod
    def __len__(self):
        return 0

@classmethod
    def __subclasshook__(cls, C):
        if cls is Sized:
            return _check_methods(C, "__len__")
        return NotImplemented

class Container(metaclass=ABCMeta):

__slots__ = ()

@abstractmethod
    def __contains__(self, x):
        return False

@classmethod
    def __subclasshook__(cls, C):
        if cls is Container:
            return _check_methods(C, "__contains__")
        return NotImplemented

class Collection(Sized, Iterable, Container):

__slots__ = ()

@classmethod
    def __subclasshook__(cls, C):
        if cls is Collection:
            return _check_methods(C,  "__len__", "__iter__", "__contains__")
        return NotImplemented

class Callable(metaclass=ABCMeta):

__slots__ = ()

@abstractmethod
    def __call__(self, *args, **kwds):
        return False

@classmethod
    def __subclasshook__(cls, C):
        if cls is Callable:
            return _check_methods(C, "__call__")
        return NotImplemented

### SETS ###

class Set(Collection):

"""A set is a finite, iterable container.

This class provides concrete generic implementations of all
    methods except for __contains__, __iter__ and __len__.

To override the comparisons (presumably for speed, as the
    semantics are fixed), redefine __le__ and __ge__,
    then the other operations will automatically follow suit.
    """

__slots__ = ()

def __le__(self, other):
        if not isinstance(other, Set):
            return NotImplemented
        if len(self) > len(other):
            return False
        for elem in self:
            if elem not in other:
                return False
        return True

def __lt__(self, other):
        if not isinstance(other, Set):
            return NotImplemented
        return len(self) < len(other) and self.__le__(other)

def __gt__(self, other):
        if not isinstance(other, Set):
            return NotImplemented
        return len(self) > len(other) and self.__ge__(other)

def __ge__(self, other):
        if not isinstance(other, Set):
            return NotImplemented
        if len(self) < len(other):
            return False
        for elem in other:
            if elem not in self:
                return False
        return True

def __eq__(self, other):
        if not isinstance(other, Set):
            return NotImplemented
        return len(self) == len(other) and self.__le__(other)

@classmethod
    def _from_iterable(cls, it):
        '''Construct an instance of the class from any iterable input.

Must override this method if the class constructor signature
        does not accept an iterable for an input.
        '''
        return cls(it)

def __and__(self, other):
        if not isinstance(other, Iterable):
            return NotImplemented
        return self._from_iterable(value for value in other if value in self)

__rand__ = __and__

def isdisjoint(self, other):
        'Return True if two sets have a null intersection.'
        for value in other:
            if value in self:
                return False
        return True

def __or__(self, other):
        if not isinstance(other, Iterable):
            return NotImplemented
        chain = (e for s in (self, other) for e in s)
        return self._from_iterable(chain)

__ror__ = __or__

def __sub__(self, other):
        if not isinstance(other, Set):
            if not isinstance(other, Iterable):
                return NotImplemented
            other = self._from_iterable(other)
        return self._from_iterable(value for value in self
                                   if value not in other)

def __rsub__(self, other):
        if not isinstance(other, Set):
            if not isinstance(other, Iterable):
                return NotImplemented
            other = self._from_iterable(other)
        return self._from_iterable(value for value in other
                                   if value not in self)

def __xor__(self, other):
        if not isinstance(other, Set):
            if not isinstance(other, Iterable):
                return NotImplemented
            other = self._from_iterable(other)
        return (self - other) | (other - self)

__rxor__ = __xor__

def _hash(self):
        """Compute the hash value of a set.

Note that we don't define __hash__: not all sets are hashable.
        But if you define a hashable set type, its __hash__ should
        call this function.

This must be compatible __eq__.

All sets ought to compare equal if they contain the same
        elements, regardless of how they are implemented, and
        regardless of the order of the elements; so there's not much
        freedom for __eq__ or __hash__.  We match the algorithm used
        by the built-in frozenset type.
        """
        MAX = sys.maxsize
        MASK = 2 * MAX + 1
        n = len(self)
        h = 1927868237 * (n + 1)
        h &= MASK
        for x in self:
            hx = hash(x)
            h ^= (hx ^ (hx << 16) ^ 89869747)  * 3644798167
            h &= MASK
        h = h * 69069 + 907133923
        h &= MASK
        if h > MAX:
            h -= MASK + 1
        if h == -1:
            h = 590923713
        return h

Set.register(frozenset)

class MutableSet(Set):
    """A mutable set is a finite, iterable container.

This class provides concrete generic implementations of all
    methods except for __contains__, __iter__, __len__,
    add(), and discard().

To override the comparisons (presumably for speed, as the
    semantics are fixed), all you have to do is redefine __le__ and
    then the other operations will automatically follow suit.
    """

__slots__ = ()

@abstractmethod
    def add(self, value):
        """Add an element."""
        raise NotImplementedError

@abstractmethod
    def discard(self, value):
        """Remove an element.  Do not raise an exception if absent."""
        raise NotImplementedError

def remove(self, value):
        """Remove an element. If not a member, raise a KeyError."""
        if value not in self:
            raise KeyError(value)
        self.discard(value)

def pop(self):
        """Return the popped value.  Raise KeyError if empty."""
        it = iter(self)
        try:
            value = next(it)
        except StopIteration:
            raise KeyError
        self.discard(value)
        return value

def clear(self):
        """This is slow (creates N new iterators!) but effective."""
        try:
            while True:
                self.pop()
        except KeyError:
            pass

def __ior__(self, it):
        for value in it:
            self.add(value)
        return self

def __iand__(self, it):
        for value in (self - it):
            self.discard(value)
        return self

def __ixor__(self, it):
        if it is self:
            self.clear()
        else:
            if not isinstance(it, Set):
                it = self._from_iterable(it)
            for value in it:
                if value in self:
                    self.discard(value)
                else:
                    self.add(value)
        return self

def __isub__(self, it):
        if it is self:
            self.clear()
        else:
            for value in it:
                self.discard(value)
        return self

MutableSet.register(set)

### MAPPINGS ###

class Mapping(Collection):

__slots__ = ()

"""A Mapping is a generic container for associating key/value
    pairs.

This class provides concrete generic implementations of all
    methods except for __getitem__, __iter__, and __len__.

"""

@abstractmethod
    def __getitem__(self, key):
        raise KeyError

def get(self, key, default=None):
        'D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None.'
        try:
            return self[key]
        except KeyError:
            return default

def __contains__(self, key):
        try:
            self[key]
        except KeyError:
            return False
        else:
            return True

def keys(self):
        "D.keys() -> a set-like object providing a view on D's keys"
        return KeysView(self)

def items(self):
        "D.items() -> a set-like object providing a view on D's items"
        return ItemsView(self)

def values(self):
        "D.values() -> an object providing a view on D's values"
        return ValuesView(self)

def __eq__(self, other):
        if not isinstance(other, Mapping):
            return NotImplemented
        return dict(self.items()) == dict(other.items())

__reversed__ = None

Mapping.register(mappingproxy)

class MappingView(Sized):

__slots__ = '_mapping',

def __init__(self, mapping):
        self._mapping = mapping

def __len__(self):
        return len(self._mapping)

def __repr__(self):
        return '{0.__class__.__name__}({0._mapping!r})'.format(self)

class KeysView(MappingView, Set):

__slots__ = ()

@classmethod
    def _from_iterable(self, it):
        return set(it)

def __contains__(self, key):
        return key in self._mapping

def __iter__(self):
        yield from self._mapping

KeysView.register(dict_keys)

class ItemsView(MappingView, Set):

__slots__ = ()

@classmethod
    def _from_iterable(self, it):
        return set(it)

def __contains__(self, item):
        key, value = item
        try:
            v = self._mapping[key]
        except KeyError:
            return False
        else:
            return v is value or v == value

def __iter__(self):
        for key in self._mapping:
            yield (key, self._mapping[key])

ItemsView.register(dict_items)

class ValuesView(MappingView):

__slots__ = ()

def __contains__(self, value):
        for key in self._mapping:
            v = self._mapping[key]
            if v is value or v == value:
                return True
        return False

def __iter__(self):
        for key in self._mapping:
            yield self._mapping[key]

ValuesView.register(dict_values)

class MutableMapping(Mapping):

__slots__ = ()

"""A MutableMapping is a generic container for associating
    key/value pairs.

This class provides concrete generic implementations of all
    methods except for __getitem__, __setitem__, __delitem__,
    __iter__, and __len__.

"""

@abstractmethod
    def __setitem__(self, key, value):
        raise KeyError

@abstractmethod
    def __delitem__(self, key):
        raise KeyError

__marker = object()

def pop(self, key, default=__marker):
        '''D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
          If key is not found, d is returned if given, otherwise KeyError is raised.
        '''
        try:
            value = self[key]
        except KeyError:
            if default is self.__marker:
                raise
            return default
        else:
            del self[key]
            return value

def popitem(self):
        '''D.popitem() -> (k, v), remove and return some (key, value) pair
           as a 2-tuple; but raise KeyError if D is empty.
        '''
        try:
            key = next(iter(self))
        except StopIteration:
            raise KeyError
        value = self[key]
        del self[key]
        return key, value

def clear(self):
        'D.clear() -> None.  Remove all items from D.'
        try:
            while True:
                self.popitem()
        except KeyError:
            pass

def update(*args, **kwds):
        ''' D.update([E, ]**F) -> None.  Update D from mapping/iterable E and F.
            If E present and has a .keys() method, does:     for k in E: D[k] = E[k]
            If E present and lacks .keys() method, does:     for (k, v) in E: D[k] = v
            In either case, this is followed by: for k, v in F.items(): D[k] = v
        '''
        if not args:
            raise TypeError("descriptor 'update' of 'MutableMapping' object "
                            "needs an argument")
        self, *args = args
        if len(args) > 1:
            raise TypeError('update expected at most 1 arguments, got %d' %
                            len(args))
        if args:
            other = args[0]
            if isinstance(other, Mapping):
                for key in other:
                    self[key] = other[key]
            elif hasattr(other, "keys"):
                for key in other.keys():
                    self[key] = other[key]
            else:
                for key, value in other:
                    self[key] = value
        for key, value in kwds.items():
            self[key] = value

def setdefault(self, key, default=None):
        'D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D'
        try:
            return self[key]
        except KeyError:
            self[key] = default
        return default

MutableMapping.register(dict)

### SEQUENCES ###

class Sequence(Reversible, Collection):

"""All the operations on a read-only sequence.

Concrete subclasses must override __new__ or __init__,
    __getitem__, and __len__.
    """

__slots__ = ()

@abstractmethod
    def __getitem__(self, index):
        raise IndexError

def __iter__(self):
        i = 0
        try:
            while True:
                v = self[i]
                yield v
                i += 1
        except IndexError:
            return

def __contains__(self, value):
        for v in self:
            if v is value or v == value:
                return True
        return False

def __reversed__(self):
        for i in reversed(range(len(self))):
            yield self[i]

def index(self, value, start=0, stop=None):
        '''S.index(value, [start, [stop]]) -> integer -- return first index of value.
           Raises ValueError if the value is not present.

Supporting start and stop arguments is optional, but
           recommended.
        '''
        if start is not None and start < 0:
            start = max(len(self) + start, 0)
        if stop is not None and stop < 0:
            stop += len(self)

i = start
        while stop is None or i < stop:
            try:
                v = self[i]
                if v is value or v == value:
                    return i
            except IndexError:
                break
            i += 1
        raise ValueError

def count(self, value):
        'S.count(value) -> integer -- return number of occurrences of value'
        return sum(1 for v in self if v is value or v == value)

Sequence.register(tuple)
Sequence.register(str)
Sequence.register(range)
Sequence.register(memoryview)

class ByteString(Sequence):

"""This unifies bytes and bytearray.

XXX Should add all their methods.
    """

__slots__ = ()

ByteString.register(bytes)
ByteString.register(bytearray)

class MutableSequence(Sequence):

__slots__ = ()

"""All the operations on a read-write sequence.

Concrete subclasses must provide __new__ or __init__,
    __getitem__, __setitem__, __delitem__, __len__, and insert().

"""

@abstractmethod
    def __setitem__(self, index, value):
        raise IndexError

@abstractmethod
    def __delitem__(self, index):
        raise IndexError

@abstractmethod
    def insert(self, index, value):
        'S.insert(index, value) -- insert value before index'
        raise IndexError

def append(self, value):
        'S.append(value) -- append value to the end of the sequence'
        self.insert(len(self), value)

def clear(self):
        'S.clear() -> None -- remove all items from S'
        try:
            while True:
                self.pop()
        except IndexError:
            pass

def reverse(self):
        'S.reverse() -- reverse *IN PLACE*'
        n = len(self)
        for i in range(n//2):
            self[i], self[n-i-1] = self[n-i-1], self[i]

def extend(self, values):
        'S.extend(iterable) -- extend sequence by appending elements from the iterable'
        for v in values:
            self.append(v)

def pop(self, index=-1):
        '''S.pop([index]) -> item -- remove and return item at index (default last).
           Raise IndexError if list is empty or index is out of range.
        '''
        v = self[index]
        del self[index]
        return v

def remove(self, value):
        '''S.remove(value) -- remove first occurrence of value.
           Raise ValueError if the value is not present.
        '''
        del self[self.index(value)]

def __iadd__(self, values):
        self.extend(values)
        return self

MutableSequence.register(list)
MutableSequence.register(bytearray)  # Multiply inheriting, see ByteString

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