docs: def readlines(path, encoding="utf-8", skiplines=None, nlines=None, strip='right'):
      """skip n lines and fetch the next n lines.
      
      :param skiplines: default None, skip first n lines
      :param nlines: default None, yield next n lines
      :param strip: default None, available option 'left', 'right', 'both'
      
      **中文文档**
      
      跳过前#skiplines行, 然后读取#nlines行。可对字符串进行strip预处理。
      """
      strip_method = str(strip).lower()
      if strip_method in _strip_method_mapping:
          strip_func = _strip_method_mapping[strip_method]
      else:
          raise ValueError("'strip' keyword has to be one of "
                           "None, 'left', 'right', 'both'.")
      
      with open(path, "rb") as file:        
          if skiplines:
              for _ in range(skiplines):
                  next(file)
          
          if nlines:
              for _ in range(nlines):
                  yield strip_func(next(file).decode(encoding))
          else:
              for line in file:
                  yield strip_func(line.decode(encoding))