code: protected List<PType> cloneListType(List<PType> types)
  	{
  		List<PType> r = new LinkedList<PType>();
  		for (PType type : types)
  		{
  			r.add(type.clone());
  		}
  		return r;
  	}
docs: Clone a list of PTypes (and return a typed list)
  
  @param types the
  list to clone
  @return a Typed list of PTypes