Returns a list of all DeviceDataLoaders. If you need a specific DeviceDataLoader, access via the relevant property (`train_dl`, `valid_dl`, etc) as the index of DLs in this list is not guaranteed to remain constant.

def dls(self)->List[DeviceDataLoader]:
        "Returns a list of all DeviceDataLoaders. If you need a specific DeviceDataLoader, access via the relevant property (`train_dl`, `valid_dl`, etc) as the index of DLs in this list is not guaranteed to remain constant."
        res = [self.train_dl, self.fix_dl, self.single_dl]
        # Preserve the original ordering of Train, Valid, Fix, Single, Test Data Loaders
        # (Unknown/not verified as of 1.0.47 whether there are other methods explicitly using DLs their list index)
        if self.valid_dl: res.insert(1, self.valid_dl)
        return res if not self.test_dl else res + [self.test_dl]