code: function () {
              var order = this.options.fieldOrder || this.fieldOrder;
  
              this.subs.detachElems();
              if (!this.hasSetupFields()) {
                  this.setupFields();
              }
              this.$el.html(this.template(this._getTemplateVars()));
  
              if (order && order.length) {
                  order = order.slice(0);
                  while (order.length) {
                      this.subs.renderByKey(order.shift(), { useLocation: true });
                  }
              } else {
                  this.subs.renderAppend();
              }
  
              return this;
          }
docs: If your subviews (aka the fields) set in the schema aren't setup yet, then this method
  does that. Regardless, this method renders the shell template, and then renders all
  subViews. If your template has an element with data-fields defined, the fields will be
  appended to that. Otherwise they will be directly appended to the template.
  @memberOf Backbone.FormView#
  @return {Backbone.FormView}