day9 - line simulation

yes, maybe positive example of using macro - to allow my get-x being
used as PLACE in setf

but other modifications require variable.
and that's not quite what i want.

day9-test-bigger.txt

@@ -0,0 +1,8 @@
+R 5
+U 8
+L 8
+D 3
+R 17
+D 10
+L 25
+U 20