@JuanFMontesinos: I got the error
  File "/usr/local/lib/python2.7/dist-packages/torch/optim/adam.py", line 29, in __init__
    super(Adam, self).__init__(params, defaults)
  File "/usr/local/lib/python2.7/dist-packages/torch/optim/optimizer.py", line 39, in __init__
    self.add_param_group(param_group)
  File "/usr/local/lib/python2.7/dist-packages/torch/optim/optimizer.py", line 169, in add_param_group
    raise ValueError("some parameters appear in more than one parameter group")
ValueError: some parameters appear in more than one parameter group