which are connected to the three lights respectively.
Hard toss a switch, so that a light burned; the second switch to put it in the middle, then the corresponding will always flash; the last switch is open, the corresponding light has been lit;
Suppose the house lights for a, b, c, corresponding to the switch A, B, C; first open the switch A, 10 minutes after the closure of A, open B, the door is bright b, hot is a cold is c.
