It's a difficult time for all of us. We must stay aware of ongoing developments. At the same time obsessing about them adds stress to our lives -- while also weakening our immune systems. With that in mind, here's something to think about that's not COVID-19.

What would graphs with 0, 1, or 2 nodes look like? Presumably, a graph with no nodes is simply no nodes. That 's easy. (Will your program work properly when the user asks for a ring, star, or wheel with 0 nodes?) How about 1 node? What is a ring with one node? What about a wheel or a star with one node? What about any of these with two nodes? It's an interesting challenge to think about how to write code so that it deals with these situations correctly.

A link must have two distinct nodes at its end. Links aren't allowed to link a node to itself. In NetLog (and because PyLogo copies NetLogo conventions in PyLogo), attempting to link a node to itself produces an error message.

More or less. A one-node wheel is identical to a one-node star. They are both a single node positioned in the center of the screen.  A one-node ring is identical to a one-node random graph. They are both a single node positioned at the top of the ring. So in both cases, you have only one node, but they are (initially) positioned in different places.