much less test code (s-exps) needed because compiler defaults to main

but some compilation outside needed, hence clean_compile

test/register/interpreter/test_change.rb

@@ -4,7 +4,7 @@ class AddChange < MiniTest::Test
   include Ticker
 
   def setup
-    @input = s(:statements, s(:class, :Space, s(:derives, nil), s(:statements, s(:function, :Integer, s(:name, :main), s(:parameters), s(:statements, s(:return, s(:operator_value, :+, s(:int, 5), s(:int, 7))))))))
+    @input = s(:statements, s(:return, s(:operator_value, :+, s(:int, 5), s(:int, 7))))
     @state_events = {}
     @instruction_events = []
     super