def prumer(*args):
    soucet=0.0
    for i in args:
        soucet+=i
    return soucet/len(args)

>>> prumer(1,2,3,4)
--> 2.5

>>> prumer(1,2,3,4,8,12,1)
--> 4.428571428571429

>>> prumer(1,2)
--> 1.5
