src/transformers/models/distilbert/modeling_distilbert.py/DistilBertForMaskedLM/__init__
class DistilBertForMaskedLM:    def __init__(self, config: PretrainedConfig):
        super().__init__(config)

        self.activation = get_activation(config.activation)

        self.distilbert = DistilBertModel(config)
        self.vocab_transform = nn.Linear(config.dim, config.dim)
        self.vocab_layer_norm = nn.LayerNorm(config.dim, eps=1e-12)
        self.vocab_projector = nn.Linear(config.dim, config.vocab_size)

        # Initialize weights and apply final processing
        self.post_init()

        self.mlm_loss_fct = nn.CrossEntropyLoss()