nl_tokens: WritableStream API exposed for controllers .
pl_tokens: function WritableStreamAddWriteRequest ( stream ) { assert ( IsWritableStreamLocked ( <mask> ) === true ) ; assert ( stream . _state === 'writable' ) ; const promise = new Promise ( ( resolve , reject ) => { const writeRequest = { _resolve : resolve , _reject : reject } ; stream . _writeRequests . push ( writeRequest ) ; } ) ; return promise ; }