Call Snap! procedure from JavaScript

I'm making some blocks and I'm wondering how you can call Snap! functions from JavaScript.

Edit: apparently passing the procedure to the JSFunction block results in a Context object?

You should probably use the API.

I need to call a procedure that was passed as a block input.

Read the code for map.

In which file? It's certainly not in maps.js

Actually - I found the solution. You use proc.evaluate().