If we find that condition was set to "Unacceptable", we set shelf_id to None — but we don’t store condition itself in the class instance. When to use Python dataclasses—and when not to use them ...

As an FYI, nosferatu-man's and my solutions are better than S. Carton's, but require Python 2.4. The "key" parameter to sort/sorted does a "Decorate-Sort-Undecorate"[1] automatically, whereas the ...