About mask_token in SimMIM codes

[YangGangZhiQi]

Hi, thanks for this great work. After reading codes, I have a question about self.mask_token in SimMIM projects. What the role of self.mask_token in the init func of SwinTransformerForSimMIM? It sames like adding another learnable params in the model. what would happen if deleting this param?

Hope for your answer.