ref: 95d87ae1d14c74b85c1247d03ad3fc71e61c0d8b
parent: 734f289a2795aac3441810ae49a731c8c347fb42
author: phil9 <telephil9@gmail.com>
date: Sun Jan 31 23:31:39 EST 2021
difftohtml: tidy up code use patterns instead of ifs factor code into user-defined function