python平均値を求めるウィジェット

def start():
    print('          ，         
')
    num = input()
    num1 = num.split(',')
    try:
        while True:
            num1.remove(',')
    except:
        pass
    try:
        r=list(map(float,num1))
        avg=sum(r)/len(r)
        print('   :{}'.format(avg))
    except:
        print('
           
')
        start()
        
start()