code: function watchFile(file, cb, partial) {
      setAbsolutePath(file);
      storeDirectory(file);
      if (!watched_files[file.fullPath]) {
        if (use_fs_watch) {
          (function() {
            watched_files[file.fullPath] = fs.watch(file.fullPath, function() {
              typeof cb === "function" && cb(file);
            });
            partial && cb(file);
          })(file, cb);
        } else {
          (function(file, cb) {
            watched_files[file.fullPath] = true;
            fs.watchFile(file.fullPath, {interval: 150}, function() {
              typeof cb === "function" && cb(file);
            });
            partial && cb(file);
          })(file, cb);
        }
      }
    }
docs: Watches the file passed and its containing directory on change calls given listener with file object