src/transformers/models/efficientformer/modeling_efficientformer.py/EfficientFormerSelfAttention/train
class EfficientFormerSelfAttention:    def train(self, mode=True):
        super().train(mode)
        if mode and hasattr(self, "ab"):
            del self.ab
        else:
            self.ab = self.attention_biases[:, self.attention_bias_idxs]