code: def sha_github_file(cls, config, repo_file, repository_api, repository_branch):
          
  
          repo_file_sha = None
  
          cfg = config.get_conf()
          github_token = cfg['sortinghat']['identities_api_token']
          headers = {"Authorization": "token " + github_token}
  
          url_dir = repository_api + "/git/trees/" + repository_branch
          logger.debug("Gettting sha data from tree: %s", url_dir)
          raw_repo_file_info = requests.get(url_dir, headers=headers)
          raw_repo_file_info.raise_for_status()
          for rfile in raw_repo_file_info.json()['tree']:
              if rfile['path'] == repo_file:
                  logger.debug("SHA found: %s, ", rfile["sha"])
                  repo_file_sha = rfile["sha"]
                  break
  
          return repo_file_sha
docs: Return the GitHub SHA for a file in the repository