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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:

def _one_hidden(self, l:int)->Tensor:
        "Return one hidden state."
        nh = (self.n_hid if l != self.n_layers - 1 else self.emb_sz) // self.n_dir
        return one_param(self).new(1, self.bs, nh).zero_()