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

        self.distilbert = DistilBertModel(config)
        self.qa_outputs = nn.Linear(config.dim, config.num_labels)
        if config.num_labels != 2:
            raise ValueError(f"config.num_labels should be 2, but it is {config.num_labels}")

        self.dropout = nn.Dropout(config.qa_dropout)

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