<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def unhook_wnd_proc(self):

 """Restore previous Window message handler"""

        if not self.__local_wnd_proc_wrapped:
            return
        SetWindowLong(self.__local_win_handle,
                        GWL_WNDPROC,
                        self.__old_wnd_proc)

        ## Allow the ctypes wrapper to be garbage collected
        self.__local_wnd_proc_wrapped = None