code: function walk_deep(path, match, iterator, callback) {
    walk_flat(path_normalize(path), function (path, next) {
      fs.lstat(path, function (err, stats) {
        if (err) {
          next(err);
          return;
        }
  
        if (stats.isDirectory()) {
          walk_deep(path, match, iterator, next);
          return;
        }
  
        if (match(path)) {
          iterator(path, stats, next);
          return;
        }
  
        next();
      });
    }, callback);
  }
docs: walk_deep(path, match, iterator, callback) -> void - path (String): Path to iterate through - match (Function): Path test whenever iterator should be executed or not - iterator (Function): Will be fired on each element within `path` - callback (Function): Will be fired once all files were processed  Walks through given `path` with all it's nested childs calling `iterator(path, callback)` for each found file.