# define your states
STATE_OFF = 0
STATE_HEATING = 1
STATE_DONE = 2

while True:
    # Read inputs (buttons, sensors, etc) and save the results in variables

    # Now do different things based on which state we're in!
    if state == STATE_OFF:
        # Do stuff specific to this state
        outputs.off() # Example to turn the "outputs" off

        # Decide if we should go to another state
        if onButton pressed:
            heater.on()
            state = STATE_HEATING
    elif state == STATE_HEATING:
        # Do stuff specific to this state
        # Decide if we should go to another state
    elif state == STATE_DONE:
        # Do stuff specific to this state
        # Decide if we should go to another state
    else:
        # Where should we go by default?