Why this pyrhon code stops counting at 2009 and not at 2010?

Question

ans = list(range(1980, 2010))
max_ans = len(ans)
print(max_ans)
counter = 0

while counter <= max_ans - 1:
an = ans[counter]
print (an)
counter = counter + 1

Answer 1

That's how range() works. range(a, b) goes from a to b-1.

Answer 2

Thanks for your quick answer 😊