Build, test, and debug regular expressions
Parses an HTML table body with ID 'ec_table_body', likely from the China Southern Airlines (Cz) B2B booking portal, to extract flight schedule data. Each table row is captured with named groups for route indicator (IsRoute), flight number (FlightNo), origin and destination airport codes, and departure date/time and arrival time. Uses the 'gs' flags (global + dotall) so '.' matches newlines across multi-line HTML. Useful for scraping structured flight information from airline booking systems.