import _thread
import time
from machine import Pin

led1 = Pin(18, Pin.OUT)
led2 = Pin(19, Pin.OUT)
led3 = Pin(12, Pin.OUT)

#------------------------
def blink1():
    while True:
        led1.on()
        time.sleep(0.5)
        led1.off()
        time.sleep(0.5)

#------------------------
def blink2():
    while True:
        led2.on()
        time.sleep(0.250)
        led2.off()
        time.sleep(0.250)

#------------------------
def blink3():
    while True:
        led3.on()
        time.sleep(0.125)
        led3.off()
        time.sleep(0.125)

#------------------------
def greet():
    while True:
        print("Das ist präemptives Multitasking...")
        time.sleep(2)

#------------------------
# Starte den Blink-Thread
_thread.start_new_thread(blink1, ())
_thread.start_new_thread(blink2, ())
_thread.start_new_thread(blink3, ())

#------------------------
# Hauptthread führt greet() aus
greet()