author: youpy
rewrite: s/[\?&;](?:fr(?:om)?|track|ref|FM)=(?:r(?:ss(?:all)?|df)|atom)([&;].*)?$/defined($1) ? $1 : ''/e
author: youpy
rewrite: s/[\?&;](?:fr(?:om)?|track|ref|FM)=(?:r(?:ss(?:all)?|df)|atom)([&;].*)?$/defined($1) ? $1 : ''/e