WeakMap (melange.Js.WeakMap)

type t('k, 'v);

let make: unit => t('k, 'v);

let get: key:Js.dict('k) => t('k, 'v) => option('v);

let has: key:Js.dict('k) => t('k, 'v) => bool;

let set: key:Js.dict('k) => value:'v => t('k, 'v) => t('k, 'v);

let delete: key:Js.dict('k) => t('k, 'v) => bool;