#3. Python did the mistake of not having a var keyword. When you have nested closures you don't know if you are assigning a variable in the outer scope or the i

#3. Python did the mistake of not having a var keyword. When you have nested closures you don't know if you are assigning a variable in the outer scope or the inner. You have to use hacks like creating an array of length 1 in the outer scope if you want to modify it in the inner scope otherwise you create new variables in the inner scope each time you try to make an assignment. Now they created a new "nonlocal"-keyword to cope with this but it wasn't added until version 3.0. https://www.python.org/dev/peps/pep-3104/ https://www.python.org/dev/peps/pep-3104/ has a great summary of all this.