How can I tell if an element in an array is a reference?
Consider the following code:
$a = ['a1', 'a2'];
$b = ['b1', &$a];
var_dump($b);
The output of var_dump($b) is:
array(2) {
  [0]=>
  string(2) "b1"
  [1]=>
  &array(2) {
    [0]=>
    string(2) "a1"
    [1]=>
    string(2) "a2"
  }
}
As you can see, var_dump() knows that array $a is by reference inside array $b.
Is there a way to tell that an element of an array is actually a reference?
