instance method retrieve_object

# File actionpack/lib/action_view/helpers/form_helper.rb, line 1122
      def retrieve_object(object)
        if object
          object
        elsif @template_object.instance_variable_defined?("@#{@object_name}")
          @template_object.instance_variable_get("@#{@object_name}")
        end
      rescue NameError
        # As @object_name may contain the nested syntax (item[subobject]) we need to fallback to nil.
        nil
      end