Returns a list of pairs of account and block hash representing the
        head block starting for accounts from **wallet**

        :param wallet: Wallet to return frontiers for
        :type wallet: str

        :raises: :py:exc:`nano.rpc.RPCException`

        >>> rpc.wallet_frontiers(
        ...     wallet="000D1BAEC8EC208142C99059B393051BAC8380F9B5A2E6B2489A277D81789F3F"
        ... )
        {
            "xrb_3e3j5tkog48pnny9dmfzj1r16pg8t1e76dz5tmac6iq689wyjfpi00000000": "000D1BAEC8EC208142C99059B393051BAC8380F9B5A2E6B2489A277D81789F3F"
        }

def wallet_frontiers(self, wallet):
        """
        Returns a list of pairs of account and block hash representing the
        head block starting for accounts from **wallet**

        :param wallet: Wallet to return frontiers for
        :type wallet: str

        :raises: :py:exc:`nano.rpc.RPCException`

        >>> rpc.wallet_frontiers(
        ...     wallet="000D1BAEC8EC208142C99059B393051BAC8380F9B5A2E6B2489A277D81789F3F"
        ... )
        {
            "xrb_3e3j5tkog48pnny9dmfzj1r16pg8t1e76dz5tmac6iq689wyjfpi00000000": "000D1BAEC8EC208142C99059B393051BAC8380F9B5A2E6B2489A277D81789F3F"
        }

        """

        wallet = self._process_value(wallet, 'wallet')

        payload = {"wallet": wallet}

        resp = self.call('wallet_frontiers', payload)

        return resp.get('frontiers') or {}