code: def _write_recordio(f, data):
      
      length = len(data)
      f.write(struct.pack('I', _kmagic))
      f.write(struct.pack('I', length))
      pad = (((length + 3) >> 2) << 2) - length
      f.write(data)
      f.write(padding[pad])
docs: Writes a single data point as a RecordIO record to the given file.