code: def get_ns_commands(self, cmd_name):
          
          namespace, command = _split_ns_command(cmd_name)
          if not namespace:
              # Name space not given, look for the commands
              spaces = self.__find_command_ns(command)
              if not spaces:
                  # Unknown command
                  raise ValueError("Unknown command {0}".format(command))
              else:
                  # Return a sorted list of tuples
                  return sorted((namespace, command) for namespace in spaces)
  
          # Single match
          return [(namespace, command)]
docs: Retrieves the possible name spaces and commands associated to the given
          command name.
  
          :param cmd_name: The given command name
          :return: A list of 2-tuples (name space, command)
          :raise ValueError: Unknown command name