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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 ripple_withdrawal(self, amount, address, currency):
 """ Returns true if successful. """

        data = {'amount': amount, 'address': address, 'currency': currency}
        response = self._post("ripple_withdrawal/", data=data,
                              return_json=True)
        return self._expect_true(response)