text: <?php
  
  function f1() {
      debug_print_backtrace();
  }
  
  function f2($arg1, $arg2) {
      f1();
      yield; // force generator
  }
  
  function f3($gen) {
      $gen->rewind(); // trigger run
  }
  
  $gen = f2('foo', 'bar');
  f3($gen);
  
  ?>
  