code: function filter(err, files) {
      if (err) return self.emit('error', err);
  
      var kjud = files.filter(function filterfiles(file) {
        return (/(\d)\.kju$/).test(file);
      });
  
      // if we don't have any files we don't really need to emit 'recovered' so
      // no need to check for the length here. We are only gonna use the length
      // if there are files.
      processed = kjud.length;
      kjud.forEach(read);
    }
docs: filter all none `.kju` files out of the array.
  
  @param {Error} err Set when a error occurred
  @param {Array} files Files to filter
  @api private