:mod:`tkinter`: the types :class:`!_tkinter.Tcl_Obj` (wrapper for Tcl objects),
:class:`!_tkinter.tktimertoken` (obtained by calling ``createtimerhandler()``
on a :attr:`Tk <tkinter.Tk.tk>` application) and :class:`!_tkinter.tkapp`
(the runtime type of Tk applications) are now immutable.
Patch by Bénédikt Tran.
