code: def authenticate(self, request, **kwargs):
          
  
          self.request = request
          if not self.request:
              return None
  
          state = self.request.GET.get('state')
          code = self.request.GET.get('code')
          nonce = kwargs.pop('nonce', None)
  
          if not code or not state:
              return None
  
          reverse_url = self.get_settings('OIDC_AUTHENTICATION_CALLBACK_URL',
                                          'oidc_authentication_callback')
  
          token_payload = {
              'client_id': self.OIDC_RP_CLIENT_ID,
              'client_secret': self.OIDC_RP_CLIENT_SECRET,
              'grant_type': 'authorization_code',
              'code': code,
              'redirect_uri': absolutify(
                  self.request,
                  reverse(reverse_url)
              ),
          }
  
          # Get the token
          token_info = self.get_token(token_payload)
          id_token = token_info.get('id_token')
          access_token = token_info.get('access_token')
  
          # Validate the token
          payload = self.verify_token(id_token, nonce=nonce)
  
          if payload:
              self.store_tokens(access_token, id_token)
              try:
                  return self.get_or_create_user(access_token, id_token, payload)
              except SuspiciousOperation as exc:
                  LOGGER.warning('failed to get or create user: %s', exc)
                  return None
  
          return None
docs: Authenticates a user based on the OIDC code flow.