How to change GRU to LSTM in Chatbot Tutorial

My recommendations need to be used both in the training function and in the evaluation function when setting the decode initial state.

Example code:

 # Set initial decoder hidden state to the encoder's final hidden state
if encoder.model_type == 'GRU':
    decoder_hidden = encoder_hidden[:decoder.n_layers]
    
elif encoder.model_type == 'LSTM':
    #Get the encoder final h_hidden_state
    encoder_h_hidden, encoder_c_hidden= encoder_hidden
    decoder_h_hidden = encoder_h_hidden[:decoder.n_layers]
    decoder_c_hidden = encoder_c_hidden[:decoder.n_layers]
    # Recombine the final hidden states as hidden tuple
    decoder_hidden = (decoder_h_hidden, decoder_c_hidden)