By setting guest_name, guest_email, guest_location, or guest_referral to any
truthy value, a prompt will be display. By setting it to a string (instead of
true), that string will be displayed. I'm not sure how I feel about this kind
of tri-state setting (true/false/string), but it does reduce the number of
settings/options. The alternative is to have a separate boolean and string
setting for each prompt (which I first considered).

So, as of now:

guest_name = false <- no prompt for Guest's name
guest_name = "" <- no prompt for Guest's name
guest_name = true (the default) <- default prompt text for Guest's name
guest_name = "Enter your name, dude" <- replaces prompt text for Guest's name

For enter trailing white-space and ctrl-a codes, use string literals, e.g.
guest_name: "\x01hEnter your name, dude: "