This challenge features a broad range of tricky patterns (e.g., multi-part emails, phone numbers with extensions, variable date formats including leap years, IPv4 and IPv6 with invalids, color codes in hex and functional formats with valid/invalid ranges, bracket balancing requiring advanced recursion or lookbehind, repeated group capturing, valid vs invalid URLs, and a negative lookahead example). These items force advanced techniques such as negative lookbehind/lookahead, group repetition, str... (truncated)