docs: function output() {
  	if (argv.output) {
  		return Promise.all([
  			fs
  				.outputFile(
  					argv.output,
  					argv.map ? Buffer.concat([concat.content, Buffer.from(getSourceMappingURL())]) : concat.content
  				)
  				.then(() => log('write', argv.output)),
  			argv.map
  				? fs.outputFile(`${argv.output}.map`, concat.sourceMap).then(() => log('write', `${argv.output}.map`))
  				: undefined,
  		]);
  	}
  	process.stdout.write(concat.content);
  	return Promise.resolve();
  }