def append_dims(x, target_dims):
    """Appends dimensions to the end of a tensor until it has target_dims dimensions.
    From https://github.com/crowsonkb/k-diffusion/blob/master/k_diffusion/utils.py"""
    dims_to_append = target_dims - x.ndim
    if dims_to_append < 0:
        raise ValueError(
            f"input has {x.ndim} dims but target_dims is {target_dims}, which is less"
        )
    return x[(...,) + (None,) * dims_to_append]
Appends dimensions to the end of a tensor until it has target_dims dimensions.
    From https://github.com/crowsonkb/k-diffusion/blob/master/k_diffusion/utils.py
extern/ldm_zero123/models/diffusion/sampling_util.py