src/transformers/models/visual_bert/modeling_visual_bert.py/VisualBertAttention/__init__
class VisualBertAttention:    def __init__(self, config):
        super().__init__()
        self.self = VisualBertSelfAttention(config)
        self.output = VisualBertSelfOutput(config)
        self.pruned_heads = set()