def __init__(self, groups=None):
        super(GroupedRequirements, self).__init__(NamedRequirements)
        self.groups = groups or self.default_groups
        self.filename = None
        self.create_default_groups()
def __init__(self, path=None, resolver=None):
        self._path = path or ()
        if not resolver:
            resolver = Resolver()
        self._resolver = resolver