@begin: scope:[]  from
  [0] (byte) col#0 ← (byte) 0
  to:@1
@1: scope:[]  from @begin
  [1] phi()
  [2] call main 
  to:@end
@end: scope:[]  from @1
  [3] phi()
main: scope:[main]  from @1
  [4] *((const void()**) KERNEL_IRQ#0) ← &interrupt(KERNEL_MIN)(void()) irq()
  to:main::@1
main::@1: scope:[main]  from main main::@2
  [5] (byte) col#2 ← phi( main/(byte) col#0 main::@2/(byte) col#1 )
  to:main::@2
main::@2: scope:[main]  from main::@1
  [6] (byte) col#1 ← ++ (byte) col#2
  to:main::@1
irq: scope:[irq]  from
  asm { lda$dc0d  }
  [8] *((const byte*) BGCOL#0) ← (byte) col#0
  to:irq::@return
irq::@return: scope:[irq]  from irq
  [9] return 
  to:@return
