A Sound you can use as a placeholder.

Some Sounds have parameters that require a Sound to be present even if you're not really using that parameter. For instance Replicator has a SharedSounds parameter that has to have a Sound in it.

Usually these parameters will have Constants in them as placeholders. When I see a Constant in my flow I'm sometimes not sure if I intended it to do something or if it is just a placeholder. So I made Nil.

Nil is probably the most boring class imaginable. It has no parameters and just results in the value zero. (You can take that as a challenge to think of a more boring class!)

It's just a re-encapsulation of a Constant with a value zero.

But it says "placeholder" to me more clearly than a Constant.