I just used python pexpect [0] for a fun project. I believe pexpect was inspired by the original Unix expect command.
I used it to let aider suggest and run shell commands [1]. This is handy, so aider can offer to run the code it just wrote for you, run migrations, install dependencies, etc.
Using pexepect makes it easy for aider to run interactive shell commands and capture their output. This allows aider to fix bugs or suggest next steps based on the command’s output, error messages, etc.