lam is not defined

[ooochen-30]

@beginner-sketch dear writer, i want to run the code, but meet a error. is there something wrong in the code.
File "/media/xxx/xxx/GMRL-main/main.py", line 215, in main
train(device, model, dataset, n, n_source)
File "/media/xxx/xxx/GMRL-main/main.py", line 73, in train
loss = loss_reg + lam * feature_loss
NameError: name 'lam' is not defined