@abc.abstractmethod<EOL><INDENT>def search_among_functions(self, function_ids):<DEDENT>
pass<EOL>
Execute this search among the given list of functions.

        :param function_ids: list of functions
        :type function_ids: ``osid.id.IdList``
        :raise: ``NullArgument`` -- ``function_ids`` is ``null``

        *compliance: mandatory -- This method must be implemented.*