PHP: Extract Values on Specific Key in Array

I wrote tiny utility method - which is for extracting values on specific key in array.

Code

  function extractValuesForSpecificKey(array& $sourceArray, $key){
    $retArray = array();
    foreach ($sourceArray as $sourceElem){
      $retArray[] = $sourceElem[$key];
    }
    return $retArray;
   }

Example

  $source = array(
     array('id' => 1, 'name' =>'Joe'),
     array('id' => 2, 'name' =>'Chris'),
  );

  $result = extractValuesForSpecificKey($source, 'id');
  var_dump($result);

The result should be:

array(2) {
  [0]=>
  int(1)
  [1]=>
  int(2)
}