Use the Serial Console to check that the timer never exceeds the wait time you
Experiment with different delay times and see when the switch behaves erratically.
Add a second LED, and modify the sketch so that when it turns off one LED,
it turns on the other LED.
Modify the sketch so that it causes the LED to blink for about 500 ms forever,
and uses the switch not to turn the LED
OFF, but to
change the blink time from 500 ms to 1000 ms.