def get_function_vault_session(self):
raise Unimplemented()<EOL>
Gets the session for retrieving function to vault mappings.

        return: (osid.authorization.FunctionVaultSession) - a
                ``FunctionVaultSession``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_function_vault()`` is
                ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_function_vault()`` is ``true``.*