nl_tokens: Fetch data . If expired load from url and store at key
pl_tokens: function fetch ( store , key , url , options ) { options = Object . assign ( { } , DEFAULT_LOAD_OPTIONS , options ) ; options . cacheControl = parseCacheControl ( options . cacheControl ) ; if ( ! key ) { return Promise . resolve ( { body : undefined , duration : 0 , headers : { } , key , status : 400 } ) ; } return doFetch ( store , key , <mask> , options ) ; }