src/transformers/models/bert/modeling_tf_bert.py/TFBertNSPHead/__init__
class TFBertNSPHead:    def __init__(self, config: BertConfig, **kwargs):
        super().__init__(**kwargs)

        self.seq_relationship = tf.keras.layers.Dense(
            units=2,
            kernel_initializer=get_initializer(config.initializer_range),
            name="seq_relationship",
        )