def get_groups(self, username):
        """ Get a user's groups

        :param username: 'key' attribute of the user
        :type username: string
        :rtype: list of groups
        """
        try:
            return self.users[username]['groups']
        except Exception as e:
            raise UserDoesntExist(username, self.backend_name)
Get a user's groups

        :param username: 'key' attribute of the user
        :type username: string
        :rtype: list of groups