code: def create_temporary_ca_file(anchor_list):
      
      try:
          f, fname = tempfile.mkstemp()
          for a in anchor_list:
              s = a.output(fmt="PEM")
              l = os.write(f, s)
          os.close(f)
      except:
          return None
      return fname
docs: Concatenate all the certificates (PEM format for the export) in
      'anchor_list' and write the result to file to a temporary file
      using mkstemp() from tempfile module. On success 'filename' is
      returned, None otherwise.
  
      If you are used to OpenSSL tools, this function builds a CAfile
      that can be used for certificate and CRL check.
  
      Also see create_temporary_ca_file().