Hi ptrblck,
Using troch.stack as:
all_classes=torch.stack( head_features_var[0], head_features_var[1], head_features_var[2], head_features_var[3], head_features_var[4], head_features_var[5], head_features_var[6], tail_features_mean_var[7],tail_features_mean_var[8],tail_features_mean_var[9])
generates the following error:
TypeError:  stack() takes from 1 to 2 positional arguments but 10 were given