1 files changed, 851 insertions, 0 deletions
diff --git a/venv/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_internal/utils/misc.py b/venv/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_internal/utils/misc.py
new file mode 100644
index 0000000..db84a7c
--- /dev/null
+++ b/venv/lib/python3.7/site-packages/pip-10.0.1-py3.7.egg/pip/_internal/utils/misc.py
@@ -0,0 +1,851 @@
+from __future__ import absolute_import
+import contextlib
+import errno
+import io
+import locale
+# we have a submodule named 'logging' which would shadow this if we used the
+# regular name:
+import logging as std_logging
+import os
+import posixpath
+import re
+import shutil
+import stat
+import subprocess
+import sys
+import tarfile
+import zipfile
+from collections import deque
+from pip._vendor import pkg_resources
+# NOTE: retrying is not annotated in typeshed as on 2017-07-17, which is
+#       why we ignore the type on this import.
+from pip._vendor.retrying import retry  # type: ignore
+from pip._vendor.six import PY2
+from pip._vendor.six.moves import input
+from pip._internal.compat import console_to_str, expanduser, stdlib_pkgs
+from pip._internal.exceptions import InstallationError
+from pip._internal.locations import (
+    running_under_virtualenv, site_packages, user_site, virtualenv_no_global,
+    write_delete_marker_file,
+)
+if PY2:
+    from io import BytesIO as StringIO
+else:
+    from io import StringIO
+__all__ = ['rmtree', 'display_path', 'backup_dir',
+           'ask', 'splitext',
+           'format_size', 'is_installable_dir',
+           'is_svn_page', 'file_contents',
+           'split_leading_dir', 'has_leading_dir',
+           'normalize_path',
+           'renames', 'get_prog',
+           'unzip_file', 'untar_file', 'unpack_file', 'call_subprocess',
+           'captured_stdout', 'ensure_dir',
+           'ARCHIVE_EXTENSIONS', 'SUPPORTED_EXTENSIONS',
+           'get_installed_version']
+logger = std_logging.getLogger(__name__)
+BZ2_EXTENSIONS = ('.tar.bz2', '.tbz')
+XZ_EXTENSIONS = ('.tar.xz', '.txz', '.tlz', '.tar.lz', '.tar.lzma')
+ZIP_EXTENSIONS = ('.zip', '.whl')
+TAR_EXTENSIONS = ('.tar.gz', '.tgz', '.tar')
+ARCHIVE_EXTENSIONS = (
+    ZIP_EXTENSIONS + BZ2_EXTENSIONS + TAR_EXTENSIONS + XZ_EXTENSIONS)
+SUPPORTED_EXTENSIONS = ZIP_EXTENSIONS + TAR_EXTENSIONS
+try:
+    import bz2  # noqa
+    SUPPORTED_EXTENSIONS += BZ2_EXTENSIONS
+except ImportError:
+    logger.debug('bz2 module is not available')
+try:
+    # Only for Python 3.3+
+    import lzma  # noqa
+    SUPPORTED_EXTENSIONS += XZ_EXTENSIONS
+except ImportError:
+    logger.debug('lzma module is not available')
+def import_or_raise(pkg_or_module_string, ExceptionType, *args, **kwargs):
+    try:
+        return __import__(pkg_or_module_string)
+    except ImportError:
+        raise ExceptionType(*args, **kwargs)
+def ensure_dir(path):
+    """os.path.makedirs without EEXIST."""
+    try:
+        os.makedirs(path)
+    except OSError as e:
+        if e.errno != errno.EEXIST:
+            raise
+def get_prog():
+    try:
+        prog = os.path.basename(sys.argv[0])
+        if prog in ('__main__.py', '-c'):
+            return "%s -m pip" % sys.executable
+        else:
+            return prog
+    except (AttributeError, TypeError, IndexError):
+        pass
+    return 'pip'
+# Retry every half second for up to 3 seconds
+@retry(stop_max_delay=3000, wait_fixed=500)
+def rmtree(dir, ignore_errors=False):
+    shutil.rmtree(dir, ignore_errors=ignore_errors,
+                  onerror=rmtree_errorhandler)
+def rmtree_errorhandler(func, path, exc_info):
+    """On Windows, the files in .svn are read-only, so when rmtree() tries to
+    remove them, an exception is thrown.  We catch that here, remove the
+    read-only attribute, and hopefully continue without problems."""
+    # if file type currently read only
+    if os.stat(path).st_mode & stat.S_IREAD:
+        # convert to read/write
+        os.chmod(path, stat.S_IWRITE)
+        # use the original function to repeat the operation
+        func(path)
+        return
+    else:
+        raise
+def display_path(path):
+    """Gives the display value for a given path, making it relative to cwd
+    if possible."""
+    path = os.path.normcase(os.path.abspath(path))
+    if sys.version_info[0] == 2:
+        path = path.decode(sys.getfilesystemencoding(), 'replace')
+        path = path.encode(sys.getdefaultencoding(), 'replace')
+    if path.startswith(os.getcwd() + os.path.sep):
+        path = '.' + path[len(os.getcwd()):]
+    return path
+def backup_dir(dir, ext='.bak'):
+    """Figure out the name of a directory to back up the given dir to
+    (adding .bak, .bak2, etc)"""
+    n = 1
+    extension = ext
+    while os.path.exists(dir + extension):
+        n += 1
+        extension = ext + str(n)
+    return dir + extension
+def ask_path_exists(message, options):
+    for action in os.environ.get('PIP_EXISTS_ACTION', '').split():
+        if action in options:
+            return action
+    return ask(message, options)
+def ask(message, options):
+    """Ask the message interactively, with the given possible responses"""
+    while 1:
+        if os.environ.get('PIP_NO_INPUT'):
+            raise Exception(
+                'No input was expected ($PIP_NO_INPUT set); question: %s' %
+                message
+            )
+        response = input(message)
+        response = response.strip().lower()
+        if response not in options:
+            print(
+                'Your response (%r) was not one of the expected responses: '
+                '%s' % (response, ', '.join(options))
+            )
+        else:
+            return response
+def format_size(bytes):
+    if bytes > 1000 * 1000:
+        return '%.1fMB' % (bytes / 1000.0 / 1000)
+    elif bytes > 10 * 1000:
+        return '%ikB' % (bytes / 1000)
+    elif bytes > 1000:
+        return '%.1fkB' % (bytes / 1000.0)
+    else:
+        return '%ibytes' % bytes
+def is_installable_dir(path):
+    """Return True if `path` is a directory containing a setup.py file."""
+    if not os.path.isdir(path):
+        return False
+    setup_py = os.path.join(path, 'setup.py')
+    if os.path.isfile(setup_py):
+        return True
+    return False
+def is_svn_page(html):
+    """
+    Returns true if the page appears to be the index page of an svn repository
+    """
+    return (re.search(r'<title>[^<]*Revision \d+:', html) and
+            re.search(r'Powered by (?:<a[^>]*?>)?Subversion', html, re.I))
+def file_contents(filename):
+    with open(filename, 'rb') as fp:
+        return fp.read().decode('utf-8')
+def read_chunks(file, size=io.DEFAULT_BUFFER_SIZE):
+    """Yield pieces of data from a file-like object until EOF."""
+    while True:
+        chunk = file.read(size)
+        if not chunk:
+            break
+        yield chunk
+def split_leading_dir(path):
+    path = path.lstrip('/').lstrip('\\')
+    if '/' in path and (('\\' in path and path.find('/') < path.find('\\')) or
+                        '\\' not in path):
+        return path.split('/', 1)
+    elif '\\' in path:
+        return path.split('\\', 1)
+    else:
+        return path, ''
+def has_leading_dir(paths):
+    """Returns true if all the paths have the same leading path name
+    (i.e., everything is in one subdirectory in an archive)"""
+    common_prefix = None
+    for path in paths:
+        prefix, rest = split_leading_dir(path)
+        if not prefix:
+            return False
+        elif common_prefix is None:
+            common_prefix = prefix
+        elif prefix != common_prefix:
+            return False
+    return True
+def normalize_path(path, resolve_symlinks=True):
+    """
+    Convert a path to its canonical, case-normalized, absolute version.
+    """
+    path = expanduser(path)
+    if resolve_symlinks:
+        path = os.path.realpath(path)
+    else:
+        path = os.path.abspath(path)
+    return os.path.normcase(path)
+def splitext(path):
+    """Like os.path.splitext, but take off .tar too"""
+    base, ext = posixpath.splitext(path)
+    if base.lower().endswith('.tar'):
+        ext = base[-4:] + ext
+        base = base[:-4]
+    return base, ext
+def renames(old, new):
+    """Like os.renames(), but handles renaming across devices."""
+    # Implementation borrowed from os.renames().
+    head, tail = os.path.split(new)
+    if head and tail and not os.path.exists(head):
+        os.makedirs(head)
+    shutil.move(old, new)
+    head, tail = os.path.split(old)
+    if head and tail:
+        try:
+            os.removedirs(head)
+        except OSError:
+            pass
+def is_local(path):
+    """
+    Return True if path is within sys.prefix, if we're running in a virtualenv.
+    If we're not in a virtualenv, all paths are considered "local."
+    """
+    if not running_under_virtualenv():
+        return True
+    return normalize_path(path).startswith(normalize_path(sys.prefix))
+def dist_is_local(dist):
+    """
+    Return True if given Distribution object is installed locally
+    (i.e. within current virtualenv).
+    Always True if we're not in a virtualenv.
+    """
+    return is_local(dist_location(dist))
+def dist_in_usersite(dist):
+    """
+    Return True if given Distribution is installed in user site.
+    """
+    norm_path = normalize_path(dist_location(dist))
+    return norm_path.startswith(normalize_path(user_site))
+def dist_in_site_packages(dist):
+    """
+    Return True if given Distribution is installed in
+    sysconfig.get_python_lib().
+    """
+    return normalize_path(
+        dist_location(dist)
+    ).startswith(normalize_path(site_packages))
+def dist_is_editable(dist):
+    """Is distribution an editable install?"""
+    for path_item in sys.path:
+        egg_link = os.path.join(path_item, dist.project_name + '.egg-link')
+        if os.path.isfile(egg_link):
+            return True
+    return False
+def get_installed_distributions(local_only=True,
+                                skip=stdlib_pkgs,
+                                include_editables=True,
+                                editables_only=False,
+                                user_only=False):
+    """
+    Return a list of installed Distribution objects.
+    If ``local_only`` is True (default), only return installations
+    local to the current virtualenv, if in a virtualenv.
+    ``skip`` argument is an iterable of lower-case project names to
+    ignore; defaults to stdlib_pkgs
+    If ``include_editables`` is False, don't report editables.
+    If ``editables_only`` is True , only report editables.
+    If ``user_only`` is True , only report installations in the user
+    site directory.
+    """
+    if local_only:
+        local_test = dist_is_local
+    else:
+        def local_test(d):
+            return True
+    if include_editables:
+        def editable_test(d):
+            return True
+    else:
+        def editable_test(d):
+            return not dist_is_editable(d)
+    if editables_only:
+        def editables_only_test(d):
+            return dist_is_editable(d)
+    else:
+        def editables_only_test(d):
+            return True
+    if user_only:
+        user_test = dist_in_usersite
+    else:
+        def user_test(d):
+            return True
+    return [d for d in pkg_resources.working_set
+            if local_test(d) and
+            d.key not in skip and
+            editable_test(d) and
+            editables_only_test(d) and
+            user_test(d)
+            ]
+def egg_link_path(dist):
+    """
+    Return the path for the .egg-link file if it exists, otherwise, None.
+    There's 3 scenarios:
+    1) not in a virtualenv
+       try to find in site.USER_SITE, then site_packages
+    2) in a no-global virtualenv
+       try to find in site_packages
+    3) in a yes-global virtualenv
+       try to find in site_packages, then site.USER_SITE
+       (don't look in global location)
+    For #1 and #3, there could be odd cases, where there's an egg-link in 2
+    locations.
+    This method will just return the first one found.
+    """
+    sites = []
+    if running_under_virtualenv():
+        if virtualenv_no_global():
+            sites.append(site_packages)
+        else:
+            sites.append(site_packages)
+            if user_site:
+                sites.append(user_site)
+    else:
+        if user_site:
+            sites.append(user_site)
+        sites.append(site_packages)
+    for site in sites:
+        egglink = os.path.join(site, dist.project_name) + '.egg-link'
+        if os.path.isfile(egglink):
+            return egglink
+def dist_location(dist):
+    """
+    Get the site-packages location of this distribution. Generally
+    this is dist.location, except in the case of develop-installed
+    packages, where dist.location is the source code location, and we
+    want to know where the egg-link file is.
+    """
+    egg_link = egg_link_path(dist)
+    if egg_link:
+        return egg_link
+    return dist.location
+def current_umask():
+    """Get the current umask which involves having to set it temporarily."""
+    mask = os.umask(0)
+    os.umask(mask)
+    return mask
+def unzip_file(filename, location, flatten=True):
+    """
+    Unzip the file (with path `filename`) to the destination `location`.  All
+    files are written based on system defaults and umask (i.e. permissions are
+    not preserved), except that regular file members with any execute
+    permissions (user, group, or world) have "chmod +x" applied after being
+    written. Note that for windows, any execute changes using os.chmod are
+    no-ops per the python docs.
+    """
+    ensure_dir(location)
+    zipfp = open(filename, 'rb')
+    try:
+        zip = zipfile.ZipFile(zipfp, allowZip64=True)
+        leading = has_leading_dir(zip.namelist()) and flatten
+        for info in zip.infolist():
+            name = info.filename
+            data = zip.read(name)
+            fn = name
+            if leading:
+                fn = split_leading_dir(name)[1]
+            fn = os.path.join(location, fn)
+            dir = os.path.dirname(fn)
+            if fn.endswith('/') or fn.endswith('\\'):
+                # A directory
+                ensure_dir(fn)
+            else:
+                ensure_dir(dir)
+                fp = open(fn, 'wb')
+                try:
+                    fp.write(data)
+                finally:
+                    fp.close()
+                    mode = info.external_attr >> 16
+                    # if mode and regular file and any execute permissions for
+                    # user/group/world?
+                    if mode and stat.S_ISREG(mode) and mode & 0o111:
+                        # make dest file have execute for user/group/world
+                        # (chmod +x) no-op on windows per python docs
+                        os.chmod(fn, (0o777 - current_umask() | 0o111))
+    finally:
+        zipfp.close()
+def untar_file(filename, location):
+    """
+    Untar the file (with path `filename`) to the destination `location`.
+    All files are written based on system defaults and umask (i.e. permissions
+    are not preserved), except that regular file members with any execute
+    permissions (user, group, or world) have "chmod +x" applied after being
+    written.  Note that for windows, any execute changes using os.chmod are
+    no-ops per the python docs.
+    """
+    ensure_dir(location)
+    if filename.lower().endswith('.gz') or filename.lower().endswith('.tgz'):
+        mode = 'r:gz'
+    elif filename.lower().endswith(BZ2_EXTENSIONS):
+        mode = 'r:bz2'
+    elif filename.lower().endswith(XZ_EXTENSIONS):
+        mode = 'r:xz'
+    elif filename.lower().endswith('.tar'):
+        mode = 'r'
+    else:
+        logger.warning(
+            'Cannot determine compression type for file %s', filename,
+        )
+        mode = 'r:*'
+    tar = tarfile.open(filename, mode)
+    try:
+        # note: python<=2.5 doesn't seem to know about pax headers, filter them
+        leading = has_leading_dir([
+            member.name for member in tar.getmembers()
+            if member.name != 'pax_global_header'
+        ])
+        for member in tar.getmembers():
+            fn = member.name
+            if fn == 'pax_global_header':
+                continue
+            if leading:
+                fn = split_leading_dir(fn)[1]
+            path = os.path.join(location, fn)
+            if member.isdir():
+                ensure_dir(path)
+            elif member.issym():
+                try:
+                    tar._extract_member(member, path)
+                except Exception as exc:
+                    # Some corrupt tar files seem to produce this
+                    # (specifically bad symlinks)
+                    logger.warning(
+                        'In the tar file %s the member %s is invalid: %s',
+                        filename, member.name, exc,
+                    )
+                    continue
+            else:
+                try:
+                    fp = tar.extractfile(member)
+                except (KeyError, AttributeError) as exc:
+                    # Some corrupt tar files seem to produce this
+                    # (specifically bad symlinks)
+                    logger.warning(
+                        'In the tar file %s the member %s is invalid: %s',
+                        filename, member.name, exc,
+                    )
+                    continue
+                ensure_dir(os.path.dirname(path))
+                with open(path, 'wb') as destfp:
+                    shutil.copyfileobj(fp, destfp)
+                fp.close()
+                # Update the timestamp (useful for cython compiled files)
+                tar.utime(member, path)
+                # member have any execute permissions for user/group/world?
+                if member.mode & 0o111:
+                    # make dest file have execute for user/group/world
+                    # no-op on windows per python docs
+                    os.chmod(path, (0o777 - current_umask() | 0o111))
+    finally:
+        tar.close()
+def unpack_file(filename, location, content_type, link):
+    filename = os.path.realpath(filename)
+    if (content_type == 'application/zip' or
+            filename.lower().endswith(ZIP_EXTENSIONS) or
+            zipfile.is_zipfile(filename)):
+        unzip_file(
+            filename,
+            location,
+            flatten=not filename.endswith('.whl')
+        )
+    elif (content_type == 'application/x-gzip' or
+            tarfile.is_tarfile(filename) or
+            filename.lower().endswith(
+                TAR_EXTENSIONS + BZ2_EXTENSIONS + XZ_EXTENSIONS)):
+        untar_file(filename, location)
+    elif (content_type and content_type.startswith('text/html') and
+            is_svn_page(file_contents(filename))):
+        # We don't really care about this
+        from pip._internal.vcs.subversion import Subversion
+        Subversion('svn+' + link.url).unpack(location)
+    else:
+        # FIXME: handle?
+        # FIXME: magic signatures?
+        logger.critical(
+            'Cannot unpack file %s (downloaded from %s, content-type: %s); '
+            'cannot detect archive format',
+            filename, location, content_type,
+        )
+        raise InstallationError(
+            'Cannot determine archive format of %s' % location
+        )
+def call_subprocess(cmd, show_stdout=True, cwd=None,
+                    on_returncode='raise',
+                    command_desc=None,
+                    extra_environ=None, unset_environ=None, spinner=None):
+    """
+    Args:
+      unset_environ: an iterable of environment variable names to unset
+        prior to calling subprocess.Popen().
+    """
+    if unset_environ is None:
+        unset_environ = []
+    # This function's handling of subprocess output is confusing and I
+    # previously broke it terribly, so as penance I will write a long comment
+    # explaining things.
+    #
+    # The obvious thing that affects output is the show_stdout=
+    # kwarg. show_stdout=True means, let the subprocess write directly to our
+    # stdout. Even though it is nominally the default, it is almost never used
+    # inside pip (and should not be used in new code without a very good
+    # reason); as of 2016-02-22 it is only used in a few places inside the VCS
+    # wrapper code. Ideally we should get rid of it entirely, because it
+    # creates a lot of complexity here for a rarely used feature.
+    #
+    # Most places in pip set show_stdout=False. What this means is:
+    # - We connect the child stdout to a pipe, which we read.
+    # - By default, we hide the output but show a spinner -- unless the
+    #   subprocess exits with an error, in which case we show the output.
+    # - If the --verbose option was passed (= loglevel is DEBUG), then we show
+    #   the output unconditionally. (But in this case we don't want to show
+    #   the output a second time if it turns out that there was an error.)
+    #
+    # stderr is always merged with stdout (even if show_stdout=True).
+    if show_stdout:
+        stdout = None
+    else:
+        stdout = subprocess.PIPE
+    if command_desc is None:
+        cmd_parts = []
+        for part in cmd:
+            if ' ' in part or '\n' in part or '"' in part or "'" in part:
+                part = '"%s"' % part.replace('"', '\\"')
+            cmd_parts.append(part)
+        command_desc = ' '.join(cmd_parts)
+    logger.debug("Running command %s", command_desc)
+    env = os.environ.copy()
+    if extra_environ:
+        env.update(extra_environ)
+    for name in unset_environ:
+        env.pop(name, None)
+    try:
+        proc = subprocess.Popen(
+            cmd, stderr=subprocess.STDOUT, stdin=subprocess.PIPE,
+            stdout=stdout, cwd=cwd, env=env,
+        )
+        proc.stdin.close()
+    except Exception as exc:
+        logger.critical(
+            "Error %s while executing command %s", exc, command_desc,
+        )
+        raise
+    all_output = []
+    if stdout is not None:
+        while True:
+            line = console_to_str(proc.stdout.readline())
+            if not line:
+                break
+            line = line.rstrip()
+            all_output.append(line + '\n')
+            if logger.getEffectiveLevel() <= std_logging.DEBUG:
+                # Show the line immediately
+                logger.debug(line)
+            else:
+                # Update the spinner
+                if spinner is not None:
+                    spinner.spin()
+    try:
+        proc.wait()
+    finally:
+        if proc.stdout:
+            proc.stdout.close()
+    if spinner is not None:
+        if proc.returncode:
+            spinner.finish("error")
+        else:
+            spinner.finish("done")
+    if proc.returncode:
+        if on_returncode == 'raise':
+            if (logger.getEffectiveLevel() > std_logging.DEBUG and
+                    not show_stdout):
+                logger.info(
+                    'Complete output from command %s:', command_desc,
+                )
+                logger.info(
+                    ''.join(all_output) +
+                    '\n----------------------------------------'
+                )
+            raise InstallationError(
+                'Command "%s" failed with error code %s in %s'
+                % (command_desc, proc.returncode, cwd))
+        elif on_returncode == 'warn':
+            logger.warning(
+                'Command "%s" had error code %s in %s',
+                command_desc, proc.returncode, cwd,
+            )
+        elif on_returncode == 'ignore':
+            pass
+        else:
+            raise ValueError('Invalid value: on_returncode=%s' %
+                             repr(on_returncode))
+    if not show_stdout:
+        return ''.join(all_output)
+def read_text_file(filename):
+    """Return the contents of *filename*.
+    Try to decode the file contents with utf-8, the preferred system encoding
+    (e.g., cp1252 on some Windows machines), and latin1, in that order.
+    Decoding a byte string with latin1 will never raise an error. In the worst
+    case, the returned string will contain some garbage characters.
+    """
+    with open(filename, 'rb') as fp:
+        data = fp.read()
+    encodings = ['utf-8', locale.getpreferredencoding(False), 'latin1']
+    for enc in encodings:
+        try:
+            data = data.decode(enc)
+        except UnicodeDecodeError:
+            continue
+        break
+    assert type(data) != bytes  # Latin1 should have worked.
+    return data
+def _make_build_dir(build_dir):
+    os.makedirs(build_dir)
+    write_delete_marker_file(build_dir)
+class FakeFile(object):
+    """Wrap a list of lines in an object with readline() to make
+    ConfigParser happy."""
+    def __init__(self, lines):
+        self._gen = (l for l in lines)
+    def readline(self):
+        try:
+            try:
+                return next(self._gen)
+            except NameError:
+                return self._gen.next()
+        except StopIteration:
+            return ''
+    def __iter__(self):
+        return self._gen
+class StreamWrapper(StringIO):
+    @classmethod
+    def from_stream(cls, orig_stream):
+        cls.orig_stream = orig_stream
+        return cls()
+    # compileall.compile_dir() needs stdout.encoding to print to stdout
+    @property
+    def encoding(self):
+        return self.orig_stream.encoding
+@contextlib.contextmanager
+def captured_output(stream_name):
+    """Return a context manager used by captured_stdout/stdin/stderr
+    that temporarily replaces the sys stream *stream_name* with a StringIO.
+    Taken from Lib/support/__init__.py in the CPython repo.
+    """
+    orig_stdout = getattr(sys, stream_name)
+    setattr(sys, stream_name, StreamWrapper.from_stream(orig_stdout))
+    try:
+        yield getattr(sys, stream_name)
+    finally:
+        setattr(sys, stream_name, orig_stdout)
+def captured_stdout():
+    """Capture the output of sys.stdout:
+       with captured_stdout() as stdout:
+           print('hello')
+       self.assertEqual(stdout.getvalue(), 'hello\n')
+    Taken from Lib/support/__init__.py in the CPython repo.
+    """
+    return captured_output('stdout')
+class cached_property(object):
+    """A property that is only computed once per instance and then replaces
+       itself with an ordinary attribute. Deleting the attribute resets the
+       property.
+       Source: https://github.com/bottlepy/bottle/blob/0.11.5/bottle.py#L175
+    """
+    def __init__(self, func):
+        self.__doc__ = getattr(func, '__doc__')
+        self.func = func
+    def __get__(self, obj, cls):
+        if obj is None:
+            # We're being accessed from the class itself, not from an object
+            return self
+        value = obj.__dict__[self.func.__name__] = self.func(obj)
+        return value
+def get_installed_version(dist_name, lookup_dirs=None):
+    """Get the installed version of dist_name avoiding pkg_resources cache"""
+    # Create a requirement that we'll look for inside of setuptools.
+    req = pkg_resources.Requirement.parse(dist_name)
+    # We want to avoid having this cached, so we need to construct a new
+    # working set each time.
+    if lookup_dirs is None:
+        working_set = pkg_resources.WorkingSet()
+    else:
+        working_set = pkg_resources.WorkingSet(lookup_dirs)
+    # Get the installed distribution from our working set
+    dist = working_set.find(req)
+    # Check to see if we got an installed distribution or not, if we did
+    # we want to return it's version.
+    return dist.version if dist else None
+def consume(iterator):
+    """Consume an iterable at C speed."""
+    deque(iterator, maxlen=0)
+# Simulates an enum
+def enum(*sequential, **named):
+    enums = dict(zip(sequential, range(len(sequential))), **named)
+    reverse = {value: key for key, value in enums.items()}
+    enums['reverse_mapping'] = reverse
+    return type('Enum', (), enums)