find happy numbers for a given interval

find_happy_numbers

import threading
import queue
import argparse
def happy_number_finder(num,re_list):
    top=0
    if len(re_list)==2:del re_list[-1]
    re_list.append(num)
    for ch in num:
        top+=(int(ch))**2
    
    if top!=1:
        happy_number_finder(str(top),re_list)
    return re_list[0]   
def threader():
    
    while True:
        value=q.get()
        try:
            re_list=[]
            result=happy_number_finder(str(value),re_list)
            happy_numbers.append(result)
        except:
            pass  
        q.task_done()
if __name__=='__main__':
    print("Usage find_happy_numbers.py upper_limit lower_limit")
    print("Large intervals can take more computational time")
    parser=argparse.ArgumentParser()
    parser.add_argument("up",help="Upper limit for interval",type=str)
    parser.add_argument("down",help="Lower limit for interval",type=str) 
    args=parser.parse_args
    print(args)
    happy_numbers=[]
    q=queue.Queue()
    for i in range(40):
        t=threading.Thread(target=threader)
        t.daemon=True
        t.start()
    
    for value in range(int(args[2]),int(args[3])+1):
        q.put(value)
    q.join()   
    print("list of happy_numbers")
    print(happy_numbers)