code: def _init(self, parser):
          
          assert isinstance(parser, argparse.ArgumentParser)
          self._init_parser(parser)
  
          self._attach_arguments()
          self._attach_subcommands()
          self.initialized = True
docs: Initialize/Build the ``argparse.ArgumentParser`` and subparsers.
  
          This internal version of ``init`` is used to ensure that all
          subcommands have a properly initialized parser.
  
          Args
          ----
          parser : argparse.ArgumentParser
              The parser for this command.