I'm creating an extremely difficult challenge that incorporates a variety of complex patterns requiring advanced regex techniques. The text sample includes: 1) an email with a plus filter and subdomains requiring special character escaping, 2) an international-format phone number with optional plus sign, spaces, and parentheses, 3) three date formats for February 29 in a leap year with different separators, 4) a pattern with a repeated two-letter block with a two-digit number in between (requiri... (truncated)