Superhero degrees of separation - introducing the breadth-first search algorithm

You might have heard how everyone is connected through six degrees of separation. Somebody you know knows somebody else who knows somebody else and so on; eventually, you can be connected to pretty much everyone on the planet. Or maybe you've heard about how Kevin Bacon is within a few degrees of separation of pretty much everybody in Hollywood. Well, I used to work at imdb.com, and I can tell you that is true, Kevin Bacon is pretty well connected, but a lot of other actors are too. Kevin Bacon is actually not the most connected actor, but I digress! We want to bring this concept of degrees of separation to our superhero dataset, where we have this virtual social network of superheroes.

Let's figure out the degrees of separation between any two superheroes in that dataset. Is the Hulk connected to Spider-Man closely? How do you find how many connections there are between any two given superheroes that we have...