docs: def _mkdir(path):
      """
      Make a directory or bail.
      """
      try:
          os.mkdir(path)
      except OSError as e:
          if e.errno == 17:
              show_error("ABORTING: Directory {0} already exists.".format(path))
          else:
              show_error("ABORTING: OSError {0}".format(e))
          sys.exit()