code: def _register_namespace_and_command(self, namespace):
          
          self._add_namespace(namespace)
          # Add the namespace for commands on this database
          cmd_name = namespace.source_name.split(".", 1)[0] + ".$cmd"
          dest_cmd_name = namespace.dest_name.split(".", 1)[0] + ".$cmd"
          self._add_namespace(Namespace(dest_name=dest_cmd_name, source_name=cmd_name))
docs: Add a Namespace and the corresponding command namespace.