The Empty List Blocks Recursion

[leoahum]

List = [0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15]
step = 4



def ResetCR (l, stp):
    K = []
    if stp != 0:
        for i in range(1, int(len(l)/stp)+1):
            K.append(l[i*stp - 1])
        l = [x for x in l if x not in K]
        stp = stp - 1
        return ResetCR(l,stp)
    if stp == 0:
        return K


F = ResetCR(List,step)

print (F)

I'm trying to change the order of a list. If the "K = []" is out side the function, it works. However, I'm wondering is there a way to keep the variable 'K' inside the function?