code: def fetch_closed_pull_requests(self):
          
  
          pull_requests = []
          verbose = self.options.verbose
          gh = self.github
          user = self.options.user
          repo = self.options.project
          if verbose:
              print("Fetching closed pull requests...")
          page = 1
          while page > 0:
              if verbose > 2:
                  print(".", end="")
  
              if self.options.release_branch:
                  rc, data = gh.repos[user][repo].pulls.get(
                      page=page, per_page=PER_PAGE_NUMBER, state='closed',
                      base=self.options.release_branch
                  )
              else:
                  rc, data = gh.repos[user][repo].pulls.get(
                      page=page, per_page=PER_PAGE_NUMBER, state='closed',
                  )
  
              if rc == 200:
                  pull_requests.extend(data)
              else:
                  self.raise_GitHubError(rc, data, gh.getheaders())
              page = NextPage(gh)
          if verbose > 2:
              print(".")
          if verbose > 1:
              print("\tfetched {} closed pull requests.".format(
                  len(pull_requests))
              )
          return pull_requests
docs: Fetch all pull requests. We need them to detect "merged_at" parameter
  
          :rtype: list
          :return: all pull requests