def _init(self, parser):
assert isinstance(parser, argparse.ArgumentParser)<EOL>self._init_parser(parser)<EOL>self._attach_arguments()<EOL>self._attach_subcommands()<EOL>self.initialized = True<EOL>
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.