anchor.diff:      start = true;
       try{
         test();
  -    } catch(AssersionException e) {
  +    } catch(AssertionException e) {
         errorMessage = e.msg;
         error = e;
         return;
  
positive.code:     }
  
      if(result == false){
        throw new AssersionException.msg("expected is ${buffer.toString()}<${expect}>, but got <${actual}>.");
      }
    }
  }
  
negative.code:   }
  }
  
  class AssertionException implements Exception {
    String msg;
    
    AssertionException.msg(this.msg) : super() ;
  }
  
  typedef bool _op(StringBuffer buffer, bool result);
  