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 is_resource_deleted(self, id):
        try:
            self.get_snapshot(id)
        except exceptions.NotFound:
            return True
        return False