This took me a minute to get, even after looking at the page about if:

https://ryelang.org/meet_rye/basics/if_either/

The tricky thing about if, and, and or --- the reason you can't implement them as functions in most languages --- is that they need to not evaluate all their arguments immediately. Otherwise:

    // Would print!
    if(false, print("oops!"))

    // Would throw  an error if the key is not present
    and(my_hashmap.has_key("key"), my_hashmap["key"])

The way that ryelang gets around this is that you pass the arguments in a "code block" surrounded by "{}", which delays its evaluation. So you write:

    // Does not print, because *if* never runs its code block arg
    if 0 { print("oops!") }

    // There's no example of *and* anywhere but my guess is you'd write this:
    and { my_hashmap.has_key("key") } { my_hashmap["key"] }