def get_authorization_session_for_vault(self, vault_id=None, proxy=None):
if vault_id is None or proxy is None:<EOL><INDENT>raise NullArgument<EOL><DEDENT>raise Unimplemented()<EOL>
Gets an ``AuthorizationSession`` which is responsible for performing authorization checks for the given vault.

        arg:    vault_id (osid.id.Id): the ``Id`` of the vault
        arg:    proxy (osid.proxy.Proxy): a proxy
        return: (osid.authorization.AuthorizationSession) - ``an
                _authorization_session``
        raise:  NotFound - ``vault_id`` not found
        raise:  NullArgument - ``vault_id`` or ``proxy`` is ``null``
        raise:  OperationFailed - ``unable to complete request``
        raise:  Unimplemented - ``supports_authorization()`` or
                ``supports_visible_federation()`` is ``false``
        *compliance: optional -- This method must be implemented if
        ``supports_authorization()`` and
        ``supports_visible_federation()`` are ``true``.*