code: def add_path_argument(cls, group, argname, dest=None, help_=None):
          
          prefixed = '%s-%s' % (cls.argument_prefix, argname)
          if dest is None:
              dest = prefixed.replace('-', '_')
              final_dest = dest[len(cls.argument_prefix) + 1:]
          else:
              final_dest = dest
              dest = '%s_%s' % (cls.argument_prefix, dest)
  
          group.add_argument('--%s' % prefixed, action='store',
                             dest=dest, help=help_)
          cls.path_arguments[dest] = final_dest
docs: Subclasses may call this to expose a path argument.
  
          Args:
              group: arparse.ArgumentGroup, the extension argument group
              argname: str, the name of the argument, will be namespaced.
              dest: str, similar to the `dest` argument of
                  `argparse.ArgumentParser.add_argument`, will be namespaced.
              help_: str, similar to the `help` argument of
                  `argparse.ArgumentParser.add_argument`.