to_catalog(pairs) that converts a list of (product, price) tuples into a dict mapping product → price, but excluding any product priced at 0 or below, using a dict comprehension.to_catalog([('pen', 10), ('demo', 0), ('book', 250)]){'pen': 10, 'book': 250}demo is dropped because its price is not positive.
{k: v for k, v in pairs} is the base shape.
Add an if filter at the end.