<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def _register_namespace_and_command(self, namespace):
 """Add a Namespace and the corresponding command 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))