Admittedly there's only a single use-case I can think of for this right now but others might be able to think of more so this is to gauge interest really.

In an AWS auto-scaling EC2 cluster you may start a long running CLI command, there's no guarantee that the instance won't be cycled while the command is running unless you run an AWS CLI command to prevent that.

It'd be cool to define commands in the yaml config file that are run before and or after any WP CLI commands.