So far, we have been working with two methods of an
:class:`argparse.ArgumentParser` instance. Let's introduce a third one,
:meth:`add_mutually_exclusive_group`. It allows for us to specify options that
-conflict with each other. Let's also change the rest of the program make the
+conflict with each other. Let's also change the rest of the program to make the
new functionality makes more sense:
we'll introduce the ``--quiet`` option,
which will be the opposite of the ``--verbose`` one::