filter.js

function transform(input) {
  var output = { read: read };
  input.onError = function (err) { return output.onError(err); };
  input.onEnd = function () { return output.onEnd(); };
  return output;

  function read(callback) {
    input.read(function (data) {
      callback(data.toUpperCase());
    });
  }
}

new-stream.js

var stream = makeMagicStream();

stream.onEnd = onEnd;
stream.onError = onError;
return stream.read(onRead);

function onRead(data) {
  console.log(data);
  return stream.read(onRead);
}

function onError(err) {
  throw err;
}

function onEnd() {
  console.log("Done");
}