Looks for the name of the softmax layer.
    :return: Softmax layer name

def _get_softmax_name(self):
    """
    Looks for the name of the softmax layer.
    :return: Softmax layer name
    """
    for layer in self.model.layers:
      cfg = layer.get_config()
      if 'activation' in cfg and cfg['activation'] == 'softmax':
        return layer.name

    raise Exception("No softmax layers found")