My go-to example for `expect` is password-based SSH. Since we're all enlightened beings these days who surely never use this anymore, there's no risk to it:

    #!/bin/bash

    expect -c "
    spawn ssh user@10.0.0.1

    expect \"password:\"
    send \"12345\r\"

    interact
    "

`interact` hands you back control to do whatever you want, but you don't actually need to do that. You can have `expect` run every command, fill out every field.

The tool you need when you're in environments you don't deserve.