{"content":"I'm creating an extremely difficult challenge requiring advanced regex techniques. This challenge combines multiple complex pattern types that would be very difficult to match with a single regex:\n\n1. Mixed format ISBN numbers (10 and 13 digit variants with different separators)\n2. Credit card numbers with varying formats and masking patterns\n3. JWT tokens with complex character patterns\n4. Custom product codes with specific validation rules\n5. MAC addresses with different separator styles\n6. IPv6 addresses with complex abbreviation patterns\n7. Latitude/longitude coordinates in varying formats\n8. Semantic version numbers with optional components\n9. Hexadecimal color codes in different formats (#RGB, #RRGGBB, rgb(), etc.)\n\nI've included similar-looking items that shouldn't match, creating the need for precise pattern matching with negative lookaheads/lookbehinds and boundary checks. Many patterns require careful handling of special characters, precise quantifiers... (truncated)