code: function toggleButton( evt ){
  
      target = evt.target;
      while ( target && !target.getAttribute( toggleMethod ) ){
        target = target.parentNode;
        if(!target) { return; }
      }
  
      currentState = target.getAttribute( menuState ) === isOpen ? isClosed : isOpen;
  
      target.setAttribute(menuState, currentState);
     
    }
docs: The open/close action is performed by toggling an attribute
  on the menu main element.
  
  First, check if the target is the menu itself. If it's a child
  keep walking up the tree until we found the main element
  where we can toggle the state.