def forward(self, input):
        #TODO confused
        input = input.view((-1, ) + input.size()[-3:])
        if self._representation in ['mv', 'residual']:
            input = self.data_bn(input)

        base_out = self.base_model(input)
        return base_out


anyone can tell me this line function?
input = input.view((-1, ) + input.size()[-3:])