docs: def sub_retab(match):
      r"""Remove all tabs and convert them into spaces.
  
      PARAMETERS:
      match -- regex match; uses re_retab pattern: \1 is text before tab,
               \2 is a consecutive string of tabs.
  
      A simple substitution of 4 spaces would result in the following:
  
          to\tlive    # original
          to    live  # simple substitution
  
      Instead, we convert tabs like the following:
  
          to\tlive    # original
          to  live    # the tab *looks* like two spaces, so we convert
                      # it to two spaces
      """
      before = match.group(1)
      tabs = len(match.group(2))
      return before + (' ' * (TAB_SIZE * tabs - len(before) % TAB_SIZE))