def default_value(self):
    """Create default model value.

    If default option was specified, then it will be deeply copied.
    None otherwise.

    Returns:
      default model value.
    """
    if self.default:
      return copy.deepcopy(self.default)
    else:
      return None
Create default model value.

    If default option was specified, then it will be deeply copied.
    None otherwise.

    Returns:
      default model value.
    
mapreduce/model.py