Pi Pico test script to calculate primes and report status in built in LED every 20 seconds

main.py

from machine import Pin, Timer
import utime, math

led = Pin(25, Pin.OUT)
tim = Timer()

pIdx = 0;
x = 0;
latestPrime=0;

def is_prime(n: int) -> bool:
    """Primality test using 6k+-1 opt."""
    if n<=3:
        return n>1
    if n%2 ==0 or n%3==0:
        return False
    i=5
    while i** 2 <=n:
        if n%i==0 or n%(i+2)==0:
            return False
        i+=6
    return True

def dah():
    led.value(1)
    utime.sleep(0.25)
    led.value(0)
    utime.sleep(0.25)
    
def dit():
    led.value(1)
    utime.sleep(0.05)
    led.value(0)
    utime.sleep(0.25)
    
def alert_flicker():
    for i in range(0,20):
        led.value(1)
        utime.sleep(0.02)
        led.value(0)
        utime.sleep(0.02)    
    utime.sleep(0.5)
    
def led_binary(myInt):
    for char in bin(myInt)[2:]:
        if char == '0':
            dit()
        else:
            dah()
    
def led_dec(myInt):
    for char in str(math.floor(myInt/1000.)):
        if int(char)>0:
            for i in range(int(char)):
                dit()
        else:
            dah()            
        utime.sleep(0.5)
            

def disp_latest_prime(timer):
    print("prime" , pIdx , " = " , latestPrime)
    alert_flicker()
#     led_binary(pIdx)
    led_dec(pIdx)

   

led.value(0)
tim.init(freq=0.05, mode=Timer.PERIODIC, callback = disp_latest_prime)
    
while True:
    x+=1
    if is_prime(x):
        latestPrime=x;
        pIdx+=1