anchor.diff:  class Filter {
   
     int _filterType;
  -
     int get filterType => _filterType;
   
     // The assertion value for this filter.
  
positive.code: 
    Filter operator &(Filter other) => Filter.and([this, other]);
    Filter operator |(Filter other) => Filter.or([this, other]);
  
    String toString() => "Filter(type=$_filterType attrName=$_attributeName val=$_assertionValue, subFilters=$_subFilters)";
  
    /**
  
negative.code:   static const int TYPE_GREATER_OR_EQUAL = 0xA5;
    static const int TYPE_LESS_OR_EQUAL = 0xA6;
  
    static const int TYPE_PRESENCE =  0x87;
    static const int TYPE_APPROXIMATE_MATCH = 0xA8;
    static const int TYPE_EXTENSIBLE_MATCH = 0xA9;
  
  