<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def balance(self, account):
 """ Return the balance, a tuple with the eth and ocn balance. :param account: Account instance to return the balance of :return: Balance tuple of (eth, ocn) """

        return Balance(self._keeper.get_ether_balance(account.address),
                       self._keeper.token.get_token_balance(account.address))