src/transformers/models/longformer/modeling_tf_longformer.py/TFLongformerPooler/__init__
class TFLongformerPooler:    def __init__(self, config: LongformerConfig, **kwargs):
        super().__init__(**kwargs)

        self.dense = tf.keras.layers.Dense(
            units=config.hidden_size,
            kernel_initializer=get_initializer(config.initializer_range),
            activation="tanh",
            name="dense",
        )