anchor.diff:  Value instructionValue = info.newInstructionValue(new HReturn(null));
   Value lengthValue = info.newLengthValue(new HReturn(null));
   
  -Range createSingleRange(Value value) => info.newRange(value, value);
  +Range createSingleRange(Value value) => info.newNormalizedRange(value, value);
   
   Range createSingleIntRange(int value) {
     return createSingleRange(info.newIntValue(value));
  
positive.code: checkAndRange(Range one, Range two, lower, upper) {
    if (lower is num) lower = info.newIntValue(lower);
    if (upper is num) upper = info.newIntValue(upper);
    Range range = info.newRange(lower, upper);
    Expect.equals(range, one & two);
  }
  
  
negative.code:     } else {
        up = arg2;
      }
      Expect.equals(info.newNormalizedRange(low, up), -range);
    }
  }
  
  