(PHP 7 >= 7.4.0, PHP 8)
ReflectionReference::fromArrayElement — Create a ReflectionReference from an array element
$array, int|string $key): ?ReflectionReferenceCreates a ReflectionReference from an array element.
arrayThe array which contains the potential reference.
keyThe key; either an int or a string.
   Returns a ReflectionReference  instance if
   $array[$key] is a reference, or null otherwise.
  
   If array is not an array, or key
   is not an int or string, a TypeError is thrown. 
   If $array[$key] does not exist,
   a ReflectionException is thrown.