docs: def cmd(binary, subcommand, *args, **kwargs):
      """
      Construct a command line for a "modern UNIX" command.
  
      Modern UNIX command do a closely-related-set-of-things and do it well.
      Examples include :code:`apt-get` or :code:`git`.
  
      :param binary: the name of the command
      :param subcommand: the subcommand used
      :param args: positional arguments (put last)
      :param kwargs: options
      :returns: list of arguments that is suitable to be passed to :code:`subprocess.Popen`
                and friends.
  
      When specifying options, the following assumptions are made:
  
      * Option names begin with :code:`--` and any :code:`_` is assumed to be a :code:`-`
      * If the value is :code:`NO_VALUE`, this is a "naked" option.
      * If the value is a string or an int, these are presented as the value of the option.
      * If the value is a list, the option will be repeated multiple times.
      * If the value is a dict, the option will be repeated multiple times, and
        its values will be :code:`<KEY>=<VALUE>`.
      """
      ret = [binary, subcommand]
      for key, value in kwargs.items():
          key = '--' + key.replace('_', '-')
          ret.extend(_keyword_arguments(value, key))
      ret.extend(args)
      return ret