def _dap_transfer_block_free_bytes(self, size):
        send = size - 5 - 4 * self._write_count
        recv = size - 4 - 4 * self._read_count
        return send, recv
Tests that the 'get_best_bid_ask' method produces the
dataset/ETHPy150Open mbedmicro/pyOCD/pyOCD/pyDAPAccess/dap_access_usb.py/_Command._dap_transfer_block_free_bytes--crossover with--dataset/ETHPy150Open mhallsmoore/qstrader/price_handler/price_handler_test.py/TestPriceHandlerSimpleCase.test_get_best_bid_ask