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 add_target_handle(self, layer):
        input_handle = layer.register_forward_hook(get_target_input)
        self.target_handle = input_handle