PHP array merging & combine for associative array

Input array= array("test"=>array("s1"=>array(),"s2"=>array()))

foreach(array_keys($free_tim) as $k=>$v){
               //echo "$v===".count($free_tim[$v])."
";
               foreach((array_keys($free_tim[$v])) as $f=>$s){
                  foreach(($free_tim[$v][$s]) as $g=>$e){
                     $te[$v][] = $e;
                  }
               }
            }


Output array = array("test"=>array())