code: function () {
                  var path, features, index = i;
  
                  save();
  
                  var dir = $re(/^@import?\s+/);
  
                  var options = (dir ? this.importOptions() : null) || {};
  
                  if (dir && (path = this.entities.quoted() || this.entities.url())) {
                      features = this.mediaFeatures();
                      if ($char(';')) {
                          features = features && new(tree.Value)(features);
                          return new(tree.Import)(path, features, options, index, env.currentFileInfo);
                      }
                  }
  
                  restore();
              }
docs: An @import directive  @import "lib";  Depending on our environemnt, importing is done differently: In the browser, it's an XHR request, in Node, it would be a file-system operation. The function used for importing is stored in `import`, which we pass to the Import constructor.