src/transformers/models/lxmert/modeling_lxmert.py/LxmertForQuestionAnswering/__init__
class LxmertForQuestionAnswering:    def __init__(self, config):
        super().__init__(config)
        # Configuration
        self.config = config
        self.num_qa_labels = config.num_qa_labels
        self.visual_loss_normalizer = config.visual_loss_normalizer

        # Lxmert backbone
        self.lxmert = LxmertModel(config)

        self.answer_head = LxmertVisualAnswerHead(config, self.num_qa_labels)

        # Weight initialization
        self.init_weights()

        # Loss function
        self.loss = CrossEntropyLoss()