code: function (attrConfigs, initialValues) {
              var self = this;
              util.each(attrConfigs, function (attrConfig, name) {
                  self.addAttr(name, attrConfig);
              });
              if (initialValues) {
                  self.set(initialValues);
              }
              return self;
          }
docs: Configures a group of attributes, and sets initial values.
  @param {Object} attrConfigs  An object with attribute name/configuration pairs.
  @param {Object} initialValues user defined initial values
  @chainable