function changeIt(objName) {
  //The image object accessed through its id we mentioned in the DIV block which is going to be visible currently
  var obj = document.getElementById(objName);
  
  //An array that hold the IDs of images that we mentioned in their DIV blocks
  var objId = new Array();
  
  //Storing the image IDs into the array starts here
  objId[0] = "rollo1";
  objId[1] = "rollo2";
  objId[2] = "rollo3";
  
  //Storing the image IDs into the array ends here
  
  //A counter variable going to use for iteration
  var i;
  
  //A variable that can hold all the other object references other than the object which is going to be visible
  var tempObj;
  
  //The following loop does the display of a single image based on its ID. The image whose ID we passed into this function will be the
  //only image that is displayed rest of the images will be hidden based on their IDs and that part has been handled by the else part
  //of the if statement within this loop.
  for(i=0;i<objId.length;i++) {
    if(objName == objId[i]) {
      obj.style.display = "block";
    } else {
      tempObj = document.getElementById(objId[i]);
      tempObj.style.display = "none";
    }
  }
  return;
}