python怎么累加变量

Question

   for i in range(0,len(row)):

     strs = i;
     print(strs)
     
     我想要strs 的值是 0,1,2,3  就是一个累加的字符串

Answer 1

s = ''

for i in range(0,5):

s += str(i)+','

print(s)

Answer 2

strs = ','.join([str(_) for _ in range(4)])
print strs