User Story 3

Your boss is keen to see your results. He asks you to write out a file
of your findings, one for each input file, in this format:

457508000
664371495 ERR
86110??36 ILL
ie the file has one account number per row. If some characters are
illegible, they are replaced by a ?. In the case of a wrong checksum, or
illegible number, this is noted in a second column indicating status.