def confirm_sign_up(self,confirmation_code,username=None):
        """
        Using the confirmation code that is either sent via email or text
        message.
        :param confirmation_code: Confirmation code sent via text or email
        :param username: User's username
        :return:
        """
        if not username:
            username = self.username
        params = {'ClientId': self.client_id,
                  'Username': username,
                  'ConfirmationCode': confirmation_code}
        self._add_secret_hash(params, 'SecretHash')
        self.client.confirm_sign_up(**params)