@begin: scope:[]  from
  [0] phi()
  to:@1
@1: scope:[]  from @begin
  [1] phi()
  [2] call main 
  to:@end
@end: scope:[]  from @1
  [3] phi()

(void()) main()
main: scope:[main]  from @1
  [4] phi()
  to:main::@1
main::@1: scope:[main]  from main main::@1
  [5] (signed word) main::i#2 ← phi( main/(signed word) -$a main::@1/(signed word) main::i#1 )
  [6] (byte*) main::sc#0 ← (const byte*) SCREEN + (signed word) main::i#2
  [7] (byte~) main::$1 ← (byte)(signed word) main::i#2
  [8] *((byte*) main::sc#0) ← (byte~) main::$1
  [9] (signed word) main::i#1 ← ++ (signed word) main::i#2
  [10] if((signed word) main::i#1!=(signed byte) $b) goto main::@1
  to:main::@return
main::@return: scope:[main]  from main::@1
  [11] return 
  to:@return
