code: function match(regex, callback) {
    return inspect(onComplete);
  
    function onComplete(filename, contents, done) {
      callback(filename, contents.match(regex), done);
      if (callback.length < 3) {
        done();
      }
    }
  }
docs: Match a regular expression in the transformed file's contents and call the given method for each file.
  @param {RegExp} regex A regular expression to test the file contents
  @param {function} callback A method to call with the filename and matches for each file