import { PersistentStorage } from '../types' ; example export class MMKVWrapper implements PersistentStorage < string | null > { private storage ; constructor ( storage ) { this . storage = storage ; } getItem ( key ) { return this . storage . getString ( key ) || null ; } removeItem ( key ) { return this . storage . delete ( key ) ; } setItem ( key , value ) { if ( value !== null ) { return this . storage . set ( key , value ) ; } return this . removeItem ( key ) ; } } interface MMKVInterface { set : ( key : string , value : boolean | string | number ) => void ; getBoolean : ( key : string ) => boolean ; getString : ( key : string ) => string | undefined ; getNumber : ( key : string ) => number ; delete : ( key : string ) => void ; getAllKeys : ( ) => string [ ] ; clearAll : ( ) => void ; }