def add(self, elem, replace=False):
        """Add a requirement.

        :param elem: a string or :class:`Requirement` instance.
        :param replace: if `True`, packages in the set with the same name will
            be removed first.
        """
        if isinstance(elem, text_type):
            elem = Requirement.coerce(elem)
        if replace and elem in self:
            self.remove(elem)
        super(Requirements, self).add(elem)
def __init__(self, path, matcher):
        super(subdirmatcher, self).__init__(matcher._root, matcher._cwd)
        self._path = path
        self._matcher = matcher
        self._always = matcher.always()

        self._files = [
            f[len(path) + 1 :] for f in matcher._files if f.startswith(path + "/")
        ]

        # If the parent repo had a path to this subrepo and the matcher is
        # a prefix matcher, this submatcher always matches.
        if matcher.prefix():
            self._always = any(f == path for f in matcher._files)