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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def generate_username(self, user_class):
 """ Generate a new username for a user """

        m = getattr(user_class, 'generate_username', None)
        if m:
            return m()
        else:
            max_length = user_class._meta.get_field(
                self.username_field).max_length
            return uuid.uuid4().hex[:max_length]