src/transformers/models/megatron_bert/modeling_megatron_bert.py/MegatronBertPreTrainingHeads/__init__
class MegatronBertPreTrainingHeads:    def __init__(self, config):
        super().__init__()
        self.predictions = MegatronBertLMPredictionHead(config)
        self.seq_relationship = nn.Linear(config.hidden_size, 2)