public function addSubmenu($title, array $attributes = array(), $location = null)
	{
		return $this->addItemInstance($this->makeSubmenu($title, $attributes), $location);
	}
public function addSubmenu($title, array $attributes = array(), $location = null)
	{
		return $this->addItemInstance($this->makeSubmenu($title, $attributes), $location);
	}
public function addSubmenu ( $ title , array $ attributes = array ( ) , $ location = null ) { return $ this -> addItemInstance ( $ this -> makeSubmenu ( $ title , $ attributes ) , $ location ) ; }
Add a submenu to the menu collection.

@param  string $title
@param  array  $attributes
@param  int    $location

@return \anlutro\Menu\Nodes\SubmenuNode
Add a submenu to the menu collection .