code: function download(input, output) {
  	if (!output) output = input.split("/").pop();
  	var file = fs.createWriteStream(output);
  	var request = http.get(input, response => { response.pipe(file); });
  }
docs: Downloads a file.
  @param {string} input The input file path, often a URL.
  @param {string} [output=input file name] The name of the downloaded file.