PHP：在一个也是一个Generator的函数中创建一个额外的Generator（用于通过引用传递）

Question

I once had a function like the following:

function f(array $xs, &$responsesOut): array { // note the &
   $ys = [];
   $responsesOut = [];
   foreach ($xs as $x) {
      $response = getResponse($x);
      $ys[] = extractYFromResponse($response);
      $responsesOut[] = $response;
   }
   return $ys;
}

This worked well, until I ran into memory problems. So I used a Generator for f with respect to the $ys:

function f(array $xs, &$responsesOut): iterable {
   $responsesOut = [];
   foreach ($xs as $x) {
      $response = getResponse($x);
      yield extractYFromResponse($response);
      $responsesOut[] = $response;
   }
}

This works, but obviously not with respect to $responsesOut (as this part is unchanged). What I now want to do is to bind a Generator (instead of an array) to $responsesOut. But given that there is no new Generator(), I cannot figure out how to do this. Maybe you can help me?