code: def env_dn_dict(self, env_prefix, cert_value):
          
          if not cert_value:
              return {}
  
          env = {}
          for rdn in cert_value:
              for attr_name, val in rdn:
                  attr_code = self.CERT_KEY_TO_LDAP_CODE.get(attr_name)
                  if attr_code:
                      env['%s_%s' % (env_prefix, attr_code)] = val
          return env
docs: Return a dict of WSGI environment variables for a client cert DN.
  
          E.g. SSL_CLIENT_S_DN_CN, SSL_CLIENT_S_DN_C, etc.
          See SSL_CLIENT_S_DN_x509 at
          https://httpd.apache.org/docs/2.4/mod/mod_ssl.html#envvars.