Get a schema by given uuid.

        :param str uuid: schema uuid to retrieve.
        :rtype: Schema
        :raises: KeyError if uuid is not registered already.

def getbyuuid(self, uuid):
        """Get a schema by given uuid.

        :param str uuid: schema uuid to retrieve.
        :rtype: Schema
        :raises: KeyError if uuid is not registered already.
        """
        if uuid not in self._schbyuuid:
            raise KeyError('uuid {0} not registered'.format(uuid))

        return self._schbyuuid[uuid]