H7RIYGQWGSQEIEZYQ7FSYJ3X4PGV7YEALOCPTUBPKLSQKHB5A6JAC
6ZB4CIW66KZMCEBTUWTRRNKQAV5WVPYX4QLFAJT5TTJ3CMS4JMXQC
2GK5DOU7ODF4WBSN3QTD3WIO52VTL2LOAXKGCDEMMAQPTEO4A4HAC
return if length($cur) <= length($prefix);
return undef if length($cur) <= length($prefix);