code: function(parser, reporter){
          var rule = this,
              count = 0;
  
          //check for use of "font-size"
          parser.addListener("property", function(event){
              if (event.property == "font-size"){
                  count++;
              }
          });
  
          //report the results
          parser.addListener("endstylesheet", function(){
              reporter.stat("font-sizes", count);
              if (count >= 10){
                  reporter.rollupWarn("Too many font-size declarations (" + count + "), abstraction needed.", rule);
              }
          });
      }
docs: initialization