code: public function isAbstractMethodInParents($name)
      {
          $interface = new ReflectionClass($this->interface);
          $parent    = $interface->getParentClass();
          while ($parent) {
              if (! $parent->hasMethod($name)) {
                  return false;
              }
              if ($parent->getMethod($name)->isAbstract()) {
                  return true;
              }
              $parent = $parent->getParentClass();
          }
  
          return false;
      }
docs: Checks whether a method is abstract in all parents or not.
  
  @param string $name Method name.
  
  @return bool true if method is abstract in parent, else false