"""atexit.py - allow programmer to define multiple exit functions to be executedupon normal program termination. One public function, register, is defined.""" __all__ = ["register"] import sys _exithandlers = []def _run_exitfuncs():    """run any registered exit functions     _exithandlers is traversed in reverse order so functions are executed    last in, first out.    """     exc_info = None    while _exithandlers:        func, targs, kargs = _exithandlers.pop()        try:            func(*targs, **kargs)        except SystemExit:            exc_info = sys.exc_info()        except:            import traceback            print >> sys.stderr, "Error in atexit._run_exitfuncs:"            traceback.print_exc()            exc_info = sys.exc_info()     if exc_info is not None:        raise exc_info[0], exc_info[1], exc_info[2]  def register(func, *targs, **kargs):    """register a function to be executed upon normal program termination     func - function to be called at exit    targs - optional arguments to pass to func    kargs - optional keyword arguments to pass to func    """    _exithandlers.append((func, targs, kargs)) if hasattr(sys, "exitfunc"):    # Assume it's another registered exit function - append it to our list    register(sys.exitfunc)sys.exitfunc = _run_exitfuncs if __name__ == "__main__":    def x1():        print "running x1"    def x2(n):        print "running x2(%r)" % (n,)    def x3(n, kwd=None):        print "running x3(%r, kwd=%r)" % (n, kwd)     register(x1)    register(x2, 12)    register(x3, 5, "bar")    register(x3, "no kwd args")