code: def register_command(parent_command, name):
      
      def wrapper(func):
          c = command(name)(func)
          parent_command.add_subcommand(c)
      return wrapper
docs: Create and register a command with a parent command.
  
      Args
      ----
      parent_comand : Command
          The parent command.
      name : str
          Name given to the created Command instance.
  
      Example
      -------
      .. testcode::
  
         mygit = Command(name='status')
  
         @register_command(mygit, 'status')
         def status():
             print 'Nothing to commit.'
  
      .. doctest::
         :hide:
  
         >>> mygit.init()
         >>> mygit.parse_args(['status'])
         Nothing to commit.