code: function(parser, reporter){
          var rule = this;
          var count = 0;
  
          //count how many times "float" is used
          parser.addListener("property", function(event){
              if (event.property.text.toLowerCase() == "float" &&
                      event.value.text.toLowerCase() != "none"){
                  count++;
              }
          });
  
          //report the results
          parser.addListener("endstylesheet", function(){
              reporter.stat("floats", count);
              if (count >= 10){
                  reporter.rollupWarn("Too many floats (" + count + "), you're probably using them for layout. Consider using a grid system instead.", rule);
              }
          });
      }
docs: initialization