Confusing in [for loop] topic

[deanhystad]

From the documents:

https://docs.python.org/3/library/stdtypes.html#range

class range(start, stop[, step])
The arguments to the range constructor must be integers (either built-in int or any object that implements the __index__ special method). If the step argument is omitted, it defaults to 1. If the start argument is omitted, it defaults to 0. If step is zero, ValueError is raised.

For a positive step, the contents of a range r are determined by the formula r[i] = start + step*i where i >= 0 and r[i] < stop.

In your example the range starts with i = 1 and continues while i < 5. Since it is not specified the step size defaults to 1. This results in i having values [1, 2, 3, 4].

print(list(range(1, 5)))

Output:
[1, 2, 3, 4]