code: def _split(expr, pat=None, n=-1):
      
  
      return _string_op(expr, Split, output_type=types.List(types.string),
                        _pat=pat, _n=n)
docs: Split each string (a la re.split) in the Series/Index by given pattern, propagating NA values.
      Equivalent to str.split().
  
      :param expr:
      :param pat: Separator to split on. If None, splits on whitespace
      :param n: not supported right now
      :return: list sequence or scalar