src/transformers/models/longformer/convert_longformer_original_pytorch_lightning_to_pytorch.py/LightningModel/__init__
class LightningModel:    def __init__(self, model):
        super().__init__()
        self.model = model
        self.num_labels = 2
        self.qa_outputs = nn.Linear(self.model.config.hidden_size, self.num_labels)