'Create an instance from a path, optionally including legacy (distutils/
setuptools/distribute) distributions.
:param path: The path to use, as a list of directories. If not specified,
sys.path is used.
:param include_egg: If True, this instance will look for and return legacy
distributions as well as those based on PEP 376.'

def __init__(self, path=None, include_egg=False):

    if (path is None):
        path = sys.path
    self.path = path
    self._include_dist = True
    self._include_egg = include_egg
    self._cache = _Cache()
    self._cache_egg = _Cache()
    self._cache_enabled = True
    self._scheme = get_scheme(u'default')
