Long Int literal - Invalid Syntax?
Just drop the L; all integers in Python 3 are long. What was long in Python 2 is now the standard int type in Python 3.
The original code doesn't have to use a long integer either; Python 2 switches to the long type transparently as needed anyway.
Note that all Python 2 support is shortly ending (no more updates after 2020/01/01), so at this point in time you'd be much better of switching tutorials and invest your time in learning Python 3. For beginner programmers I recommend Think Python, 2nd edition as it is fully updated for Python 3 and freely available online. Or pick any of the other Stack Overflow Python chatroom recommended books and tutorials
If you must stick to your current tutorial, you could install a Python 2.7 interpreter instead, and work your way through the book without having to learn how to port Python 2 to Python 3 code first. However, you'd then also have to learn how transition from Python 2 to Python 3 in addition.
You just need remove L
fact = 1Python 3.X integers support unlimited size in contrast to Python 2.X that has a separate type for long integers.