code: function(divisor) {
              var coverage;
              var percent = this.options.coverage.match(/(\d*)%$/);
  
              if (percent) {
                  coverage = 100 - parseInt(percent[1]);
  
                  if (divisor) {
                      coverage = coverage / divisor;
                  }
              }
  
              return percent ? coverage + '%' : this.options.coverage;
          }
docs: Takes the coverage option and turns it into a effect value