+%% todo : use macro, to show the statement tested.
+#(ly:progress "~a\n" (ly:expand-environment "${HOME} $HOME $$ "))
+
+
+%% very platform dependent.
+%% #(ly:font-config-display-fonts)
+
+#(ly:progress "~A\n" (ly:duration->string (ly:make-duration 2 2 3 7)))
+#(ly:parser-parse-string (ly:parser-clone parser) "foo = #1 #(ly:progress \"hello there\n\")")
+
+#(ly:progress "~a\n" (ly:truncate-list! (iota 5) 10))
+#(ly:progress "~a\n" (ly:truncate-list! (iota 10) 5))