Swift 6 cli, Arguent Parser, top-level code error [closed]

Swift 6 command line program that uses Apple's Argument Parser v1.7

macOS 26

I get this.

'main' attribute cannot be used in a module that contains top-level code

I spent a lot of time searching for top level code. There is none.

Suggestions for what to look for?

Is this an argument parser problem?