I'm creating an extremely challenging regex problem featuring multiple formats that are visually similar but require precise matching. This challenge includes:
1. ISBN numbers in different valid formats (10 and 13 digit) with various separators, requiring validation of checksum digits
2. Credit card numbers with different spacing/formatting that follow the Luhn algorithm pattern
3. IPv6 addresses in various valid forms including compressed notation
4. Programming variable names that follow speci... (truncated)