Handles the execution of Example Group

def _execute_example_group(self):
        "Handles the execution of Example Group"
        for example in self.example:
            runner = self.__class__(example, self.formatter)
            runner.is_root_runner = False
            successes, failures, skipped = runner.run(self.context)
            self.num_successes += successes
            self.num_failures += failures
            self.num_skipped += skipped