PhpParser\NodeTraverser::addVisitor PHP Method

    public function addVisitor(NodeVisitor $visitor)
    {
        $this->visitors[] = $visitor;
    }

 protected function setUp()
 {
     $this->traverser = new NodeTraverser();
     $this->visitor = new ClassVisitor();
     $this->traverser->addVisitor($this->visitor);
     $this->parser = new Parser(new Lexer());
 }