code: function() {
          var factConj = '';
          for(var key in this.causes) {
              factConj += ' ^ ' + this.causes[key].toString().substring(1).replace(/,/g, '');
          }
          for(var key in this.operatorCauses) {
              factConj += ' ^ ' + this.operatorCauses[key].toString().substring(1).replace(/,/g, '');
          }
          return factConj.substr(3) + ' -> ' + this.consequences.toString().substring(1).replace(/,/g, '');
      }
docs: Convenient method to stringify a rule.
  @returns {string}