code: function findRushJsonFolder() {
      if (!_rushJsonFolder) {
          let basePath = __dirname;
          let tempPath = __dirname;
          do {
              const testRushJsonPath = path.join(basePath, exports.RUSH_JSON_FILENAME);
              if (fs.existsSync(testRushJsonPath)) {
                  _rushJsonFolder = basePath;
                  break;
              }
              else {
                  basePath = tempPath;
              }
          } while (basePath !== (tempPath = path.dirname(basePath))); // Exit the loop when we hit the disk root
          if (!_rushJsonFolder) {
              throw new Error('Unable to find rush.json.');
          }
      }
      return _rushJsonFolder;
  }
docs: Find the absolute path to the folder containing rush.json