def groups_option(f):
    new_func = click.option("-g", "--groups",
                            help="Comma-separated list of requirement groups "
                            "to include.")(f)
    return update_wrapper(new_func, f)
def get(self, key, default=None):
        try:
            value = self[key]
        except KeyError:
            value = self._to_python(default)
        return value