code: @Override
  	public int lastIndexOf(Object elem) {
  		if (elem == null) return -1;
  		if (elem instanceof Number) return lastIndexOf(((Number)elem).intValue());
  		return -1;
  	}
docs: Returns the index of the last occurrence of the specified object in
  this list.
  
  @param   elem   the desired element.
  @return  the index of the last occurrence of the specified object in
  this list; returns -1 if the object is not found.