docs: def get_none_packages(self):
          """
          Get packages with None (not founded), recursively
          """
          not_found = set()
          for package_name, package in self.packages.items():
              if package is None:
                  not_found.add(package_name)
              else:
                  if package.packages:
                      not_found = not_found | package.get_none_packages()
          return not_found