code: 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;
  	}
docs: Imports a package to current symbol table
  @param Package $package
  @param string $id