keras/src/backend/tensorflow/trainer.py/TensorFlowTrainer/__init__
class TensorFlowTrainer:    def __init__(self):
        super().__init__()
        self.train_function = None
        self.test_function = None
        self.predict_function = None

        # Model must be created under scope of DistStrat it will be trained
        # with.
        if tf.distribute.has_strategy():
            self._distribute_strategy = tf.distribute.get_strategy()
        else:
            self._distribute_strategy = None