参考：

# -*- coding: UTF-8 -*-

l = [1,2,3,4,5,6,7];
k = 1;
for i in l:
    print(i,end= ('' if (k == len(l)) else ','));
    k += 1;

Python3 测试：

a=[1,2,3,4]
for i in range(0,len(a)):
    if i!=(len(a)-1):
        print(a[i],end=',')
    else:
        print(a[i])

参考：

import re

l=str(range(5));
m=re.search(r'\[(.*?)\]',l)
print( m.groups()[0] )