Runs the specs. Returns a tuple indicating the
        number of (succeses, failures, skipped)>

def execute(self, example_groups):
        """Runs the specs. Returns a tuple indicating the
        number of (succeses, failures, skipped)>
        """
        total_successes, total_errors, total_skipped = 0, 0, 0
        for group in example_groups:
            runner = ExampleRunner(group, self.formatter)
            successes, errors, skips = runner.run()
            total_successes += successes
            total_errors += errors
            total_skipped += skips
        return total_successes, total_errors, total_skipped