How to print key value in python for in

Question

a=[1,0,1,0]
for i in a:
    print i

This can print 1, 0, 1, 0. I want to print his array key value 0,1,2,3. How to do it

Answer 1

a=[1,0,1,0]
for i, v in enumerate(a):
    print i, v

Answer 2

a=[1,0,1,0]
for index,value in enumerate(a):
    print index

Answer 3

Line number output (line number starts from 1)

my_list = ['a', 'b', 'c']
for idx, val in enumerate(my_list, 1):
     print(idx, val)