annotated-read-stream.js

function processFile(file) {
  fs.createReadStream(file)         // open the gzipped csv file and start sending chunks of it downstream
    .pipe(zlib.createGunzip())      // once you get a chunk, decompress it and pass it downstream
    .pipe(csv())                    // convert the decompressed chunk into individual rows and values
    .on('data', processRow(row))    // if a row has a parallax measurement, calculate its position and write it to a new file
}