public function group( $name )
	{
		$name = rtrim($name, '.');
		$pref = $name . '.';
		$len = strlen($pref);
		$data = [];

		foreach( array_keys($this->items) as $key )
		{
			if( $key === $name )
			{
				$data['.'] = $this->items[$key];
			}
			else if( strlen($key) > $len && substr($key, 0, $len) === $pref )
			{
				$data[substr($key, $len)] = $this->items[$key];
			}
		}

		return new self($data);
	}