function get ($name)
  {
    if (isset($this->items[$name]))
      return $this->items[$name];
    throw new \OutOfBoundsException (sprintf ("%s is not registered on %s.%sCurrently registered: %s", $name,
      static::class, PHP_EOL, $this->items ? implode (', ', array_keys ($this->items)) : '(empty)'));
  }