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 _find_user(self, dn):
        return next(i for (i, d) in enumerate(self.directory) if d["dn"] == dn)