SubtypePlayground
The real Subtype compiler, running in your browser as WebAssembly. Edit the script: the checker answers as you type. Take a line out of needs and see what it says.
Ctrl Enter runCtrl Shift F formatTab indentGutter dots: green is an allowed call, amber is checked when it runs, red is a problem.Your script stays in this page and in the link. Install the compiler to run it for real.