docs: def _attach_module_identifier(command_dict, modulefn):
    """
    Attaches a 'module': modulename entry to each node in the dictionary.
    This is used by the help printer so that the user can tell if a command was
    included by default or via a module. 
    """
    for command in command_dict:
      command_dict[command]['module'] = modulefn
      _attach_module_identifier(command_dict[command]['children'], modulefn)