{"content":"I'm creating an extremely challenging regex problem featuring multiple formats that are visually similar but require precise matching. This challenge includes:\n1. ISBN numbers in different valid formats (10 and 13 digit) with various separators, requiring validation of checksum digits\n2. Credit card numbers with different spacing/formatting that follow the Luhn algorithm pattern\n3. IPv6 addresses in various valid forms including compressed notation\n4. Programming variable names that follow specific naming conventions\n5. Time expressions with timezone offsets in multiple formats\n\nThe challenge is exceptionally difficult because:\n- Each category has lookalikes that shouldn't be matched\n- Many patterns contain special regex characters that need escaping\n- The formats have optional components and variable whitespace\n- Several patterns might require lookaheads/lookbehinds to properly validate\n- The text contains intentional near-matches that should be excluded","func... (truncated)