text: var loop = require("serial-loop");
  var fs = require("fs");
  
  module.exports = concat;
  
  function concat (files, dest, callback) {
    fs.writeFile(dest, '', function (error) {
      if (error) return callback(error);
  
      loop(files.length, each, callback);
  
      function each (done, i) {
        fs.readFile(files[i], function (error, buffer) {
          if (error) return done(error);
  
          fs.appendFile(dest, buffer, done);
        });
      }
  
    });
  
  }
  