code: public function isNestedType()
      {
          if (!isset($this->isNestedType)) {
              $this->isNestedType = in_array(
                  'MetaModels\Filter\Setting\IWithChildren',
                  class_implements($this->typeClass, true)
              );
          }
  
          return $this->isNestedType;
      }
docs: Check if the type allows children.
  
  @return bool