code: function () {
                  var path, features, index = parserInput.i;
  
                  var dir = parserInput.$re(/^@import?\s+/);
  
                  if (dir) {
                      var options = (dir ? this.importOptions() : null) || {};
  
                      if ((path = this.entities.quoted() || this.entities.url())) {
                          features = this.mediaFeatures();
  
                          if (!parserInput.$char(';')) {
                              parserInput.i = index;
                              error('missing semi-colon or unrecognised media features on import');
                          }
                          features = features && new(tree.Value)(features);
                          return new(tree.Import)(path, features, options, index, fileInfo);
                      }
                      else {
                          parserInput.i = index;
                          error('malformed import statement');
                      }
                  }
              }
docs: An @import atrule  @import "lib";  Depending on our environment, 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.