1Though more and more projects are starting to be “primarily Python 3” or even “Python 3 only”.↩

2In fact, it is possible to change the class of an object at runtime, although this is an advanced topic, and the technique is only rarely used.↩

3It’s generally unhelpful to think about the destruction of objects in Python. Better to think of objects becoming unreachable.↩

4The formal arguments of a function are the arguments listed in the function definition.↩

5The actual arguments of a function are the arguments listed in a function call.↩