Sort contents using sort() method available to list()
        :return: None (because list().sort() doesn't return anything)

def sort(self, key=None, reverse=False):
        """
        Sort contents using sort() method available to list()
        :return: None (because list().sort() doesn't return anything)
        """
        self.log('sort()')
        self.contents.sort(key=key, reverse=reverse)
        return None