anchor.diff:  
   -record(for, {
       init :: expression(),
  -    conditions :: conditions(),
  +    conditions :: condition(),
       update :: expression(),
       loop_block :: statements(),
       line :: line()
  
positive.code: % blocks
  
  -record(if_block, {
      conditions :: conditions(),
      true_block :: statements(),
      false_block :: statements(),
      line :: line()
  
negative.code: 
  -record(while, {
      type :: (pre | post),
      conditions :: condition(),
      loop_block :: statements(),
      line :: line()
  }).
  