diff -r 59779ce322a6 -r ca48ac1d3c3e solutions1/collatz.scala
--- a/solutions1/collatz.scala	Sat Jun 22 08:39:52 2019 +0100
+++ b/solutions1/collatz.scala	Wed Jul 24 14:22:06 2019 +0100
@@ -1,6 +1,8 @@
 // Part 1 about the 3n+1 conjecture
 //==================================
 
+// generate jar with
+//   > scala -d collatz.jar  collatz.scala
 
 object CW6a { // for purposes of generating a jar