Flag-qubit Simulation of QEC with Flag qubits (https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.121.050502) using [7,1,3] Steane code. There is an advantage with simple Bell state example when $p<10^{-3}$. There is an advantage with prep meas. example when $p<1.4\times 10^{-3}$.