def __init__(self, scheme='default'):
        """
        Initialise an instance.
        :param scheme: Because locators look for most recent versions, they
                       need to know the version scheme to use. This specifies
                       the current PEP-recommended scheme - use ``'legacy'``
                       if you need to support existing distributions on PyPI.
        """
        self._cache = {}
        self.scheme = scheme
        # Because of bugs in some of the handlers on some of the platforms,
        # we use our own opener rather than just using urlopen.
        self.opener = build_opener(RedirectHandler())
        # If get_project() is called from locate(), the matcher instance
        # is set from the requirement passed to locate(). See issue #18 for
        # why this can be useful to know.
        self.matcher = None
        self.errors = queue.Queue()

        Initialise an instance.
        :param scheme: Because locators look for most recent versions, they
                       need to know the version scheme to use. This specifies
                       the current PEP-recommended scheme - use ``'legacy'``
                       if you need to support existing distributions on PyPI.
        
product/gradle-plugin/src/main/python/pip/_vendor/distlib/locators.py