//function to display or hide a given element
    function showHideItems(myItem, myButton){
    //this is the ID of the hidden item
    var myItem = document.getElementById(myItem);
    //this is the ID of the plus/minus button image
    var myButton = document.getElementById(myButton);
        if (myItem.style.display != "none") {
            //items are currently displayed, so hide them
            myItem.style.display = "none";
            swapImage(myButton,"plus");
        }
        else {
            //items are currently hidden, so display them
            myItem.style.display = "block";
            swapImage(myButton,"minus");
        }
    }

    //function to swap an image based on its current state
    
    
    //function swapImage(myImage, state) {

      //  if (state == "minus") {
        //    myImage.src = "images/minus.jpg";
        //}
        //else {
          //  myImage.src = "images/plus.jpg";
    //}
//}