resultX = 1001

def rechner(z1,z2, rechne="plus"):
    if rechne == "plus":
        resultX = z1+z2
    if rechne == "mal":
            resultX = z1 * z2
    resultX = z1 + z2
    print "resu =", resultX
    return resultX
    
andi = rechner(17,4)

print rechner(17,4,"gruber")
print resultX