public function import(Package $package, $id = null) {
		$id = is_null($id) ? $package->id : $id;
		
		//load symbols
		$this->symbols = array_merge($package->symbols, $this->symbols);
		
		//load macros
		$this->macros = array_merge($package->macros, $this->macros);
					
		//store package
		$this->packages[$id] = $package;
	}