Too Long; Didn't Read
Rust doesn't see files as files, but it sees them as modules and files inside folders as sub-modules. You can't just reference them directly with a simple import or drilled namespacing a la JavaScript or C# and use them right away. When using crate, you use the root directory to include everything. Rust can help Rust's compiler to identify it by providing a #path directive to use in our welcome code. Then we can reference it directly to call the run function directly.