def get_relationship_lookup_session(self, proxy=None):
if not self.supports_relationship_lookup():<EOL><INDENT>raise Unimplemented()<EOL><DEDENT>try:<EOL><INDENT>from . import sessions<EOL><DEDENT>except ImportError:<EOL><INDENT>raise OperationFailed()<EOL><DEDENT>proxy = self._convert_proxy(proxy)<EOL>try:<EOL><INDENT>session = sessions.RelationshipLookupSession(proxy=proxy,<EOL>runtime=self._runtime)<EOL><DEDENT>except AttributeError:<EOL><INDENT>raise OperationFailed()<EOL><DEDENT>return session<EOL>
Gets the ``OsidSession`` associated with the relationship lookup service.

        arg:    proxy (osid.proxy.Proxy): a proxy
        return: (osid.relationship.RelationshipLookupSession) - a
                ``RelationshipLookupSession``
        raise:  NullArgument - ``proxy`` is ``null``
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - ``supports_relationship_lookup()`` is
                ``false``
        *compliance: optional -- This method must be implemented if ``supports_relationship_lookup()`` is ``true``.*