@abc.abstractmethod<EOL><INDENT>def assign_qualifier_to_vault(self, qualifier_id, vault_id):<DEDENT>
pass<EOL>
Adds an existing ``Qualifier`` to a ``Vault``.

        :param qualifier_id: the ``Id`` of the ``Qualifier``
        :type qualifier_id: ``osid.id.Id``
        :param vault_id: the ``Id`` of the ``Vault``
        :type vault_id: ``osid.id.Id``
        :raise: ``AlreadyExists`` -- ``qualifier_id`` is already assigned to ``vault_id``
        :raise: ``NotFound`` -- ``qualifier_id`` or ``vault_id`` not found
        :raise: ``NullArgument`` -- ``qualifier_id`` or ``vault_id`` is ``null``
        :raise: ``OperationFailed`` -- unable to complete request
        :raise: ``PermissionDenied`` -- authorization failure

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