def init_weights(self):
        """"Init weights of hidden layer if exists."""
        super(VisionTransformerClsHead, self).init_weights()
        # Modified from ClassyVision
        if hasattr(self.layers, 'pre_logits'):
            # Lecun norm
            trunc_normal_(
                self.layers.pre_logits.weight,
                std=math.sqrt(1 / self.layers.pre_logits.in_features))
            nn.init.zeros_(self.layers.pre_logits.bias)
"Init weights of hidden layer if exists.
mmpretrain/models/heads/vision_transformer_head.py