Yeah, here it is :
dataset = dataset_manager.init_img_dataset(
    root='data',name=dataset_name
)

class MyDatasetA(dataset):
    
    def __init__(self):
        self.data = dataset
    
    def __getitem__(self,index):
        return self.data[index]
    
    def __len__(self):
        return len(self.data)