URL fetching wrapper for feedparser v.16

wrapper.js

var FeedParser = require('feedparser')
  , request = require('request')
  , STATUS_CODES = require('http').STATUS_CODES;

module.exports = function (feed, cb) {
  var parser = new FeedParser();
  var req = request(feed);
  var items = [];

  var _called = false;

  req.on('error', function (err) {
    if (!_called) {
      _called = true;
      cb(err);
    }
  });

  req.on('response', function (response) {
    if (200 !== response.statusCode) {
      var err = new Error(STATUS_CODES[response.statusCode]);
      err.code = response.statusCode;
      parser.end();
      if (!_called) {
        _called = true;
        cb(err);
      }
    }
  });

  parser.on('error', function (err) {
    if (!_called) {
      _called = true;
      cb(err);
    }
  });

  parser.on('readable', function () {
    var stream = this, item;
    while (item = stream.read()) {
      // items.push(item);
    }
  });

  parser.on('end', function () {
    if (!_called) {
      _called = true;
      cb(null, items);
    }
  });

  return req.pipe(parser);
};

is the _called latching pattern an example of unpiping or is that something else?

Unpiping is just calling stream#unpipe() - http://nodejs.org/api/stream.html#stream_readable_unpipe_destination

Thanks for the unpiping link. It seems all of my superfluous emitting problems are solved with this latching technique. Do you think it is also prudent to unpipe at the first error?