docs: def get_subparser(self, name, dest="subcommand", **kwargs):
          """Get or create subparser."""
          if name not in self.children:
              # Create the subparser.
              subparsers = self._get_subparsers(dest)
              parser = subparsers.add_parser(name, **kwargs)
              self.children[name] = NamedParser(name, parser)
          return self.children[name]