docs: function(getWebElements, locator, opt_actionResults) {
      this.getWebElements = getWebElements || null;
      this.actionResults_ = opt_actionResults;
      this.locator_ = locator;
  
      var self = this;
      WEB_ELEMENT_FUNCTIONS.forEach(function(fnName) {
        self[fnName] = function() {
          var callerError = new Error();
          var args = arguments;
          var actionFn = function(webElem) {
            return webElem[fnName].apply(webElem, args).then(null, function(e) {
              e.stack = e.stack + '\n' + callerError.stack;
              throw e;
            });
          };
          return self.applyAction_(actionFn);
        };
      });
    }