docs: def re_tab(s):
      """Return a tabbed string from an expanded one."""
      l = []
      p = 0
      for i in range(8, len(s), 8):
          if s[i - 2:i] == "  ":
              # collapse two or more spaces into a tab
              l.append(s[p:i].rstrip() + "\t")
              p = i
  
      if p == 0:
          return s
      else:
          l.append(s[p:])
          return "".join(l)