@abc.abstractmethod<EOL><INDENT>def get_authorization_vault_session(self):<DEDENT>
return<EOL>
Gets the session for retrieving authorization to vault mappings.

        :return: an ``AuthorizationVaultSession``
        :rtype: ``osid.authorization.AuthorizationVaultSession``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``Unimplemented`` -- ``supports_authorization_vault()`` is ``false``

        *compliance: optional -- This method must be implemented if
        ``supports_authorization_vault()`` is ``true``.*