Modules and imports

A module is a file that shares some of what it defines using export. Another file pulls those parts in using import. Anything not exported stays private, so a module's insides can change without breaking the files that use it.

The import lines at the top are the quickest map of a file: they say what it depends on. They are also where agents go wrong in a way you can check, by importing a function that doesn't exist or a package nobody ever published.