code: def MapByteStream(self, byte_stream, byte_offset=0, **unused_kwargs):
      
      return byte_stream[byte_offset:byte_offset + self.byte_size]
docs: Maps the data type on a byte stream.
  
      Args:
        byte_stream (bytes): byte stream.
        byte_offset (Optional[int]): offset into the byte stream where to start.
  
      Returns:
        object: mapped value.
  
      Raises:
        MappingError: if the data type definition cannot be mapped on
            the byte stream.