def commit_withdrawal(self, account_id, withdrawal_id, **params):
        """https://developers.coinbase.com/api/v2#commit-a-withdrawal"""
        response = self._post(
            'v2', 'accounts', account_id, 'withdrawals', withdrawal_id, 'commit',
            data=params)
        return self._make_api_object(response, Withdrawal)
https://developers.coinbase.com/api/v2#commit-a-withdrawal