full_dataset = Dataloder_img('//imageTr',
                                     '//labelTr',tfms.Compose([tfms.RandomRotation(45),tfms.Resize((256,256)),tfms.ToTensor()
                                                            ]))#

even when i show the len of the date set appears as 20 , even though my images are 20 and their label is 20 ,
is not suposed to be 40 ?