Did I find the right examples for you? yes no

All Samples(1)  |  Call(0)  |  Derive(0)  |  Import(1)
Allow only one instance running, I don't know why someone would want that, but well...

src/e/m/emesene-HEAD/mesinyer/emesene.py   emesene(Download)
        if options.single_instance:
            try:
                import SingleInstance
                self.single_instance = SingleInstance.SingleInstance()
                if self.single_instance.emesene_is_running():