docs: function post_token(oidc_token) {
      return new Promise((resolve, reject) => {
          dbMgr
              .updateOne("oidc_token", {
                  id_token: {
                      $eq: null
                  }
              }, {
                  $currentDate: {
                      expire_on: true
                  },
                  $set: oidc_token
              }, {upsert: true})
              .then((result) => {
                  if (result.upsertedCount === 1) {
                      return resolve(result.upsertedId._id);
                  } else {
                      return reject(new Error("No oidc_token recoreds inserted"));
                  }
              }, (err) => {
                  reject(err);
              });
      });
  }