Look up all the lists that the user is a member of.

        Args:
            username (str): The MIT username of the user
            member_type(str): The type of user, "USER" or "STRING"

        Returns:
            list of strings: names of the lists that this user is a member of

def user_lists(self, username, member_type="USER"):
        """
        Look up all the lists that the user is a member of.

        Args:
            username (str): The MIT username of the user
            member_type(str): The type of user, "USER" or "STRING"

        Returns:
            list of strings: names of the lists that this user is a member of
        """
        return self.client.service.getUserLists(username, member_type, self.proxy_id)