Return a random noun in German.

        :param plural: Return noun in plural.
        :return: Noun.

def noun(self, plural: bool = False) -> str:
        """Return a random noun in German.

        :param plural: Return noun in plural.
        :return: Noun.
        """
        key = 'plural' if \
            plural else 'noun'

        return self.random.choice(self._data[key])