code: def fetch_releases(self, package_name):
          
          package_name = self.source.normalize_package_name(package_name)
          releases = self.source.get_package_versions(package_name)
          releases_with_index_url = [(item, self.index_url) for item in releases]
          return package_name, releases_with_index_url
docs: Fetch package and index_url for a package_name.