block4.ruby

ObjectSpace.count_objects[:T_CLASS] #=> 920
Foo = Class.new
ObjectSpace.count_objects[:T_CLASS] #=> 922
``` 

Now, before we understand what `extend` is doing,  we need to first understand `Singleton Class`, so bear with me, get through the next section and we’ll then be able to understand the `extend` magic!

## The one about Singleton Class

`Singleton Class`, like its alternative name, `Anonymous Class` suggests, is anonymous, thus does not show up in the ancestor chain(!!!) That doesn’t mean we can’t access the singleton class though, in fact, there’s a handy method called `.singleton_class` that we can use.

```ruby
class Foo
end

Foo.singleton_class #=> #<Class:Foo>