src/transformers/models/longformer/modeling_longformer.py/LongformerForMaskedLM/__init__
class LongformerForMaskedLM:    def __init__(self, config):
        super().__init__(config)

        self.longformer = LongformerModel(config, add_pooling_layer=False)
        self.lm_head = LongformerLMHead(config)

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