解决方案3 :

  bytes := []rune(str)
  for from , to := 0 , len(bytes) -1 ; from < to ; from , to = from + 1, to -1{
      bytes[from] , bytes[to] = bytes[to] , bytes[from]
  }
  str = string(bytes)
  return str    

  解决方案2不能转换中文字符的问题: