as the input, the output will also be a packed sequence. When
        "bidirectional=True", output will contain a concatenation of
        the forward and reverse hidden states at each time step in the
        sequence.
  * **h_n**: tensor of shape (D * \text{num\_layers}, H_{out}) for
    unbatched input or (D * \text{num\_layers}, N, H_{out})
    containing the final hidden state for each element in the
    sequence. When "bidirectional=True", *h_n* will contain a
    concatenation of the final forward and reverse hidden states,
    respectively.

  * **c_n**: tensor of shape (D * \text{num\_layers}, H_{cell})
    for unbatched input or (D * \text{num\_layers}, N, H_{cell})
    containing the final cell state for each element in the
    sequence. When "bidirectional=True", *c_n* will contain a
    concatenation of the final forward and reverse cell states,
    respectively.

Variables: