Not sure why this works...

[Larz60+]

write your code like:

def hcf(a, b):
    print('at start: a: {}, b: {}'.format(a,b ))
    print('\nfor i in range: {}'.format(a))
    for i in range(a):
        if a > b:
            print('a > b')
            a -= b
            print('a -= b: {}'.format(a))
        elif b > a:
            print('b > a')
            b -= a
            print('b -= a: {}'.format(a))
    print('a or b: {}'.format(a or b))


hcf(int(input()), int(input()))

Get output like:

Output:
2
3
at start: a: 2, b: 3

for i in range: 2
b > a
b -= a: 2
a > b
a -= b: 1
a or b: 1