There is sadly only a little docu on the timer usage on ESP8266. It shows this example:

from machine import Timer

tim = Timer(-1)
tim.init(period=5000, mode=Timer.ONE_SHOT, callback=lambda t:print(1))
tim.init(period=2000, mode=Timer.PERIODIC, callback=lambda t:print(2))

As it uses the same timer only "2" is printed every 2 seconds, the one_shot "1" is never printed. I tried two instances of Timer(-1) but still only the last one was active. I just tried Timer(-2) and it worked, with Timer(1) and Timer(2) it also worked:

tim1 = Timer(1)
tim2 = Timer(2)
tim1.init(period=2500, mode=Timer.ONE_SHOT, callback=lambda t: print("once"))
tim2.init(period=1000, mode=Timer.PERIODIC, callback=lambda t: print("periodic"))
sleep(3.5)
tim2.deinit()

# expected printout:
# periodic
# periodic
# once
# periodic

There is one thing I'm not sure about I'd like to understand before starting a pull request on the docu:

1. Is only one virtual (RTOS -based) timer possible on the ESP8266? machine docu mentions Timer(-1) creates a virtual timer - which sounds good as it doesn't affect hardware.
2. If I create a timer with another ID, will it interfere with PWM or sleep() or time()?

By the way, great project, love it:)