'Backpropagation for sequence to sequence container. Calls Decoder container
bprop followed by Encoder container bprop.'

def bprop(self, error, inference=False, alpha=1.0, beta=0.0):

    hidden_error_list = self.decoder.bprop(error)
    self.encoder.bprop(hidden_error_list)
    return self.encoder.layers[0].deltas
