exports.seq = function(items, generator) {

  var results = [];
  var p = Promise.resolve();

  for(var i = 0, len = items.length; i < len; ++i) {
    p = p.then(generateNextHandler(items[i], i === 0))
  }

  return p.then(function(lastResult) {
    results.push(lastResult);
    return results;
  });

  // Internal helper
  function generateNextHandler(item, ignoreResult) {
    return function(prevResult) {
      if(!ignoreResult) results.push(prevResult);
      return generator(item, prevResult);
    };
  }

};

exports.delay = function(delay) {
  return new Promise(function(resolve) {
    setTimeout(resolve, delay);
  });
};