In Python, a class is a blueprint for creating objects. It defines the structure and behavior of the objects that will be created based on it. Here’s a simple example: In this example ...

but it is possible to defeat it with objects that create a reference to each other creating a “circular dependency” – see the example on page 19 of the book “Python Essential Reference ...

The example we see here is called a dictionary ... as you’ll see later on. Any mutable Python object doesn’t have a consistent hash value over its lifetime, and so can’t be used as a key.

Here’s an example of a two-dimensional ... third element from that—the 2. Note that Python doesn’t enforce any kind of dimensionality on objects like this. You could have a list of lists ...