def get_composition_lookup_session_for_repository(self, repository_id, proxy):
if repository_id is None:<EOL><INDENT>raise NullArgument()<EOL><DEDENT>if not self.supports_composition_lookup():<EOL><INDENT>raise Unimplemented()<EOL><DEDENT>try:<EOL><INDENT>from . import sessions<EOL><DEDENT>except ImportError:<EOL><INDENT>raise  <EOL><DEDENT>proxy = self._convert_proxy(proxy)<EOL>try:<EOL><INDENT>session = sessions.CompositionLookupSession(repository_id, proxy, runtime=self._runtime)<EOL><DEDENT>except AttributeError:<EOL><INDENT>raise  <EOL><DEDENT>return session<EOL>
Gets the OsidSession associated with the composition lookup
        service for the given repository.

        arg:    repository_id (osid.id.Id): the Id of the repository
        arg     proxy (osid.proxy.Proxy): a proxy
        return: (osid.repository.CompositionLookupSession) - the new
                CompositionLookupSession
        raise:  NotFound - repository_id not found
        raise:  NullArgument - repository_id is null
        raise:  OperationFailed - unable to complete request
        raise:  Unimplemented - supports_composition_lookup() or
                supports_visible_federation() is false
        compliance: optional - This method must be implemented if
                    supports_composition_lookup() and
                    supports_visible_federation() are true.