def save(self, filename=None):
        filename = Path(filename) if filename is not None else self.filename
        with filename.open("w") as f:
            f.write(self.yaml)
def __init__(self, gan=None, config=None, trainer=None):
      super().__init__(config=config, gan=gan, trainer=trainer)
      self.d_grads = None
      self.g_grads = None