VRJI37QRQWO7J2CILYHUMBC6AQLQJI53QFOTNQN4LWJXWYZ2XIMAC
7PZ4CQFVYUMSJKVCNM75VKK5JCUYU6ICHWPZXXIC3S63YJVFCP5QC
57PFNM5DCBR346EIO2FWBWKOSNRETLD26QOZJIBYOSRXAD27QLPAC
LXTTOB33N2HCUZFIUDRQGGBVHK2HODRG4NBLH6RXRQZDCHF27BSAC
if #pat == 0 then return #s end
check_eq(rfind('abc', ''), 3, 'empty pattern')