code: def _find(expr, sub, start=0, end=None):
      
  
      return _string_op(expr, Find, output_type=types.int64,
                        _sub=sub, _start=start, _end=end)
docs: Return lowest indexes in each strings in the sequence or scalar
      where the substring is fully contained between [start:end]. Return -1 on failure.
      Equivalent to standard str.find().
  
      :param expr:
      :param sub: substring being searched
      :param start: left edge index
      :param end: right edge index
      :return: sequence or scalar