code: public static function equal($objA, $objB) : bool
      {
          if ($objA === $objB) {
              return true;
          }
          if ($objA instanceof ObjectInterface && $objB instanceof ObjectInterface) {
              return $objA->equals($objB);
          }
          return $objA == $objB;
      }
docs: Determines whether two possibly-null objects are equal. Returns:
  
  - True, if $objA and $objB are both null
  - True, if $objA and $objB are both non-null,
  $objA and $objB are both ObjectInterface instances,
  and $objA->equals($objB) is true
  - True, if $objA == $objB
  - false in all other situations.
  
  @param $objA
  @param $objB
  @return boolean