code: function watchPaths(args) {
      var result = distinguishPaths(args.path)
      if (result.directories.length) {
        result.directories.forEach(function(directory) {
          watchDirectory(extend(args, {root: directory}));
        });
      }
      if (result.files.length)
        watchFiles(extend(args, {files: result.files}));
    }
docs: watch files if the paths refer to files, or directories