The description says "using lower() to ensure consistent capitalization." But the proposed solution is missing it: ```python def reference_exercise3(words: List[str]) -> List[Tuple[str, int]]: return [(k, len(list(v))) for k, v in itertools.groupby(sorted(words, key=lambda x: x[0]), key=lambda x: x[0])] ``` perhaps: ```python itertools.groupby(sorted(words, key=lambda x: x[0].lower()), key=lambda x: x[0].lower()): ```