code: function hookExtensions(_exts) {
    _lodashCollectionEach2["default"](oldHandlers, function (old, ext) {
      if (old === undefined) {
        delete require.extensions[ext];
      } else {
        require.extensions[ext] = old;
      }
    });
  
    oldHandlers = {};
  
    _lodashCollectionEach2["default"](_exts, function (ext) {
      oldHandlers[ext] = require.extensions[ext];
      registerExtension(ext);
    });
  }
docs: Register loader for given extensions.