jill/src/main/java/io/github/agentsoz/jill/util/AObjectCatalog.java
public AObject pop() {
    if (nextid > GlobalConstant.NULLID) {
      nextid--;
      AObject obj = objects[nextid];
      objects[nextid] = null;
      return obj;
    }
    return null;
  }
public AObject pop() {
    if (nextid > GlobalConstant.NULLID) {
      nextid--;
      AObject obj = objects[nextid];
      objects[nextid] = null;
      return obj;
    }
    return null;
  }
Pops (removes) the object at the top of the catalog.

@return the object at the top, or null if the catalog is empty