let readWords: string => list(string);
let theAnswer: unit => int;
let makeGreeter: string => unit => unit;
let hostname: unit => option(string);
let argv: unit => list(string);
let failGracefully: unit => string;
let die: unit => unit;
let tokenize: string => list(string);
let keys: Hashtbl.t('k, 'v) => list('k);
type rect = { mutable size: int };
let now: unit => float;