src/transformers/utils/fx.py/torch_cat
def torch_cat(tensors, dim=None, axis=None, *, out=None):
    if dim is None and axis is None:
        dim = 0
    if dim is None and axis is not None:
        dim = axis
    if dim < 0:
        dim = tensors[0].dim() + dim
    shapes = [t.shape for t in tensors]
    shape = list(shapes[0])
    concatenated_dim = sum(shape[dim] for shape in shapes)
    final_shape = shape[:dim] + [concatenated_dim] + shape[dim + 1 :]
    return torch.empty(final_shape, device="meta")