var fileSize = 500;
var ws = writeableStream()

function readAndPipe(start){
    var rs = fs.createReadStream('file', {start: start})
    rs.on('end', function(){if (ws.bytesWritten < fileSize){
        setTimeout(readAndPipe, 1000, ws.bytesWritten)
    }
    rs.pipe(ws, {end: false});
}