code: function registerHelpers(helpers) {
      var s = this;
      var names = Object.keys(helpers || {});
  
      for (var i = 0, len = names.length; i < len; i++) {
        var name = names[i];
        s.registerHelper(name, helpers[name]);
      }
  
      return s;
    }
docs: Register multiple helpers.
  @param {object} helpers - Helpers to register.
  @returns {HandlebarsEngine} - Returns self.