@abc.abstractmethod<EOL><INDENT>def call_stored_procedure(self, natural_key, enhancement):<DEDENT>
raise NotImplementedError()<EOL>
Calls a stored procedure for getting the technical key of a natural key. Returns the technical ID or None if
the given natural key is not valid.

:param T natural_key: The natural key.
:param T enhancement: Enhancement data of the dimension row.

:rtype: int|None