code: public Object getGroupById(String id) {
  		String name = elementToName.get(id);
  		if (name != null) {
  			return idToGroup.get(Dom.disAssembleId(id, name));
  		} else {
  			return null;
  		}
  	}
docs: Return the (enclosing) group for the specified element id.
  
  @param id
  element id
  @return the group object