   /* Unofficial extensions
       BZ n - sound buzzer for n milliseconds
       ST - stop
+      SE - emergency stop
       SIG - sign Logobots name
       TO x y
     */  

  }
}

void emergencyStop() {
    stepperL.setCurrentPosition(stepperL.currentPosition());
    stepperR.setCurrentPosition(stepperR.currentPosition()); 
}

void pushTo(float x, float y)

    float angle = c.substring(3).toFloat();
    turn(angle);
  } else if (c.startsWith("ST")) {
    stop();
  } else if (c.startsWith("SE")) {
    emergencyStop();
  } else if (c.startsWith("BZ")) {
    buzz(c.substring(3).toInt());
  } else if (c.startsWith("PU")) {
