perfect cubes

import math;

MAX = 30
MIN = -30

def is_perfect_cube(num):
    num = math.fabs(num)
    if math.pow(num, 1 / 3) == int(math.pow(num, 1 / 3)):
        return True;
    return False;


def cubes_test(a, b, c, d):
    for num in [a + b, b + c, c + d, a + b + c, b + c + d, a + b + c + d]:
        if not is_perfect_cube(num):
            return False
    if len(set([a, b, c, d])) < 4:
        return False
    #print("found combo:", a, b, c, d)
    print ((a, b, c, d))
    return True


def main():
    for a in range(MIN, MAX):
        #print(a)
        for b in range(MIN, MAX):
            for c in range(MIN, MAX):
                for d in range(MIN, MAX):
                    cubes_test(a, b, c, d)

main()