def function1(arg1, arg2, arg3, arg4):
    arg1 = function2(arg1)
    arg2 = function2(arg2)
    arg3 = function2(arg3)
    arg4 = function2(arg4)

def function2(arg):
    arg = dosomething(arg)
    return arg

def function1(arg1, arg2, arg3, arg4):
    for arg in listOfArguments:
        arg = function2(arg)


def function2(arg):
    arg = checkSomething(arg)
    return arg

In [1]: def func(*args):
   ...:     print len(args), args
   ...:

In [2]: func(1, 2, 3, 4)
4 (1, 2, 3, 4)

for arg in (arg1, arg2, arg3, arg4):
    # do stuff

def function1(*args):
    for arg in args:
        arg = function2(arg)