anchor.diff:    bool get isNotEmpty => value != 0;
   
     /// Returns a new mutable enum set that contains the values of this set.
  -  EnumSet<E> clone() => new EnumSet<E>.fromValue(value);
  +  EnumSet<E> clone() => EnumSet<E>.fromValue(value);
   
     @override
     int get hashCode => value.hashCode * 19;
  
positive.code: 
    @override
    String toString() {
      if (value == 0) return '0';
      int index = value.bitLength - 1;
      StringBuffer sb = new StringBuffer();
      int mask = 1 << index;
      while (index >= 0) {
        sb.write((value & mask) != 0 ? '1' : '0');
        index--;
        mask >>= 1;
      }
      return sb.toString();
    }
  }
  
  
negative.code:     }
  
      values.forEach(add);
      return _ConstEnumSet(value);
    }
  
    @override
    void set value(int mask) {
      throw UnsupportedError('EnumSet.value=');
    }
  
    @override
    bool add(E enumValue) {
      throw UnsupportedError('EnumSet.add');
    }
  
    @override
    void addAll(EnumSet<E> set) {
      throw UnsupportedError('EnumSet.addAll');
    }
  
    @override
  