old_contents: #!/usr/bin/env node
  'use strict';
  
  const fs = require('fs');
  
  const beautifyText = require('beautify-text');
  const glob = require('glob');
  const through2 = require('through2');
  
  if (process.argv.length > 2) {
  	process.argv
  		.slice(2)
  		.map(pattern => glob.sync(pattern)) // extract matched filenames
  		.reduce((acc, curr) => acc.concat(curr)) // concat all arrays into one
  		// TODO: Deduplicate
  		// .reduce((acc, curr) => acc.includes(curr) ? acc : acc.concat(curr))
  		.forEach((filename) => {
  			let fileReadStream = fs.createReadStream(filename);
  			beautifyStream(fileReadStream);
  		});
  } else {
  	beautifyStream(process.stdin);
  }
  
  function beautifyStream(stream) {
  	const beautify = through2(function (chunk, enc, callback) {
  		this.push(beautifyText(chunk.toString()));
  		callback();
  	});
  	stream
  		.pipe(beautify)
  		.pipe(process.stdout);
  }
  
new_contents: #!/usr/bin/env node
  'use strict';
  
  const fs = require('fs');
  
  const beautifyText = require('beautify-text');
  const glob = require('glob');
  const through2 = require('through2');
  
  if (process.argv.length > 2) {
  	process.argv
  		.slice(2)
  		.map(pattern => glob.sync(pattern)) // extract matched filenames
  		.reduce((acc, curr) => acc.concat(curr)) // concat all arrays into one
  		// TODO: Deduplicate
  		// .reduce((acc, curr) => acc.includes(curr) ? acc : acc.concat(curr))
  		.forEach(filename => {
  			let fileReadStream = fs.createReadStream(filename);
  			beautifyStream(fileReadStream);
  		});
  } else {
  	beautifyStream(process.stdin);
  }
  
  function beautifyStream(stream) {
  	const beautify = through2(function (chunk, enc, callback) {
  		this.push(beautifyText(chunk.toString()));
  		callback();
  	});
  	stream
  		.pipe(beautify)
  		.pipe(process.stdout);
  }
  
subject: Remove parentheses from around arrow function arg