Reset the hidden states.

def reset(self):
        "Reset the hidden states."
        [r.reset() for r in self.rnns if hasattr(r, 'reset')]
        if self.qrnn: self.hidden = [self._one_hidden(l) for l in range(self.n_layers)]
        else: self.hidden = [(self._one_hidden(l), self._one_hidden(l)) for l in range(self.n_layers)]