def combine_initial_dims(tensor: torch.Tensor) -> torch.Tensor:
    """
    Given a (possibly higher order) tensor of ids with shape
    (d1, ..., dn, sequence_length)
    Return a view that's (d1 * ... * dn, sequence_length).
    If original tensor is 1-d or 2-d, return it as is.
    """
    if tensor.dim() <= 2:
        return tensor
    else:
        return tensor.view(-1, tensor.size(-1))
Given a (possibly higher order) tensor of ids with shape
(d1, ..., dn, sequence_length)
Return a view that's (d1 * ... * dn, sequence_length).
If original tensor is 1-d or 2-d, return it as is.
allennlp/nn/util.py