src/transformers/models/big_bird/modeling_big_bird.py/BigBirdForQuestionAnswering/__init__
class BigBirdForQuestionAnswering:    def __init__(self, config, add_pooling_layer=False):
        super().__init__(config)

        config.num_labels = 2
        self.num_labels = config.num_labels
        self.sep_token_id = config.sep_token_id

        self.bert = BigBirdModel(config, add_pooling_layer=add_pooling_layer)
        self.qa_classifier = BigBirdForQuestionAnsweringHead(config)

        self.init_weights()