lstm = torch.nn.LSTM(10, 20,1)
lstm.state_dict().keys()

Output result：
Out[47]: odict_keys(['weight_ih_l0', 'weight_hh_l0', 'bias_ih_l0', 'bias_hh_l0'])

According to the calculation process of LSTM, there should be only one bias. Why do we output two bias variables, that is,‘bias_ih_l0’and’bias_hh_l0’?