code: function (filename, arg, callback) {
        console.log('*** git-hooks.js run', filename, arg);
          var hookName = path.basename(filename);
          var hooksDirname = path.resolve(path.dirname(filename), '../../.githooks', hookName);
  
          if (fsHelpers.exists(hooksDirname)) {
              var list = fs.readdirSync(hooksDirname);
              var hooks = list.map(function (hookName) {
                  return path.resolve(hooksDirname, hookName);
              });
              excludeIgnoredPaths(hooks, function (filteredHooks) {
                  runHooks(filteredHooks, [arg], callback);
              });
          } else {
              callback(0);
          }
      }
docs: Runs a git hook.
  
  @param {String} filename Path to git hook.
  @param {String} [arg] Git hook argument.
  @param {Function} callback