anchor.diff:      return a + 1;
     }
   
  +  static f7() {
  +    return 'a' + 1;
  +  }
  +
     static test() {
  -    check('StringPlusInt', f1, f2, f3, f4, f5, f6);
  +    check('StringPlusInt', f1, f2, f3, f4, f5, f6, f7);
     }
   }
   
  
positive.code:   Expect.equals(s1, s2, '\n  $name.$name1: "$s1"\n  $name.$name2: "$s2"\n');
  }
  
  void check(String name, f1, f2, [f3, f4, f5, f6]) {
    check2(name, 'f1', f1, 'f2', f2);
    if (f3 != null) check2(name, 'f1', f1, 'f3', f3);
    if (f4 != null) check2(name, 'f1', f1, 'f4', f4);
    if (f5 != null) check2(name, 'f1', f1, 'f5', f5);
    if (f6 != null) check2(name, 'f1', f1, 'f6', f6);
  }
  
  class IntPlusNull {
  
negative.code:     return a + 'a';
    }
  
    static f7() {
      return 1 + 'a';
    }
  
    static test() {
      check('IntPlusString', f1, f2, f3, f4, f5, f6, f7);
    }
  }
  
  