perimeter of squares

def perimeter():

n = 5
nL = [1,1,]
if n == 0:
    return 0
if n == 1:
    return 1 * 4
if n == 2:
    return 2 * 4
rl = [nL.append(nL[i]+nL[i-1]) for i in range(1, n)]#这里rl为[None,None,None,None]但是nL为[1,1,3,5,8]
print(rl)
return 0