Diff Coverage

    """
    if not per_depth_logits:
        raise ValueError("per_depth_logits must contain at least one prediction depth")
    if next_token_labels.ndim != 2 or next_token_labels.numel() == 0:
        raise ValueError("next_token_labels must be nonempty [B, S]")
    if next_token_labels.dtype != torch.long:
        raise ValueError("next_token_labels must have dtype torch.long")
    if normalization not in ("sequence", "valid_tokens"):
        raise ValueError("normalization must be 'sequence' or 'valid_tokens'")