错在哪里，老师

Question

错在哪里
def square_of_sum(L):
   X=0
   Y=0
   while  x<=len(L)-1:
       Y=Y+L[x]*L[x]
       x=x+1
   return Y

print square_of_sum([1,2,3,4,5])
print square_of_sum([-5,0,5,15,25])