##
3.3.1 `atexit` Example

The following simple example demonstrates how a module can initialize a counter from a file when it is imported and save the counter's updated value automatically when the program terminates without relying on the application making an explicit call into this module at termination.

      try:
          _count = int(open("/tmp/counter").read())
      except IOError:
          _count = 0

      def incrcounter(n):
          global _count
          _count = _count + n

      def savecounter():
          open("/tmp/counter", "w").write("%d" % _count)

      import atexit
      atexit.register(savecounter)