public static function setdefault(&$arr, $key, $value) {
    isset($arr[$key]) or $arr[$key] = $value;
  }
public static function setdefault(&$arr, $key, $value) {
    isset($arr[$key]) or $arr[$key] = $value;
  }
public static function setdefault ( & $ arr , $ key , $ value ) { isset ( $ arr [ $ key ] ) or $ arr [ $ key ] = $ value ; }
Sets the value of a key for the given array if that property
has not already been set.

@param &assoc $arr the object to update.
@param string $key the key to update.
@param mixed $value the value to set.
Sets the value of a key for the given array if that property has not already been set .