code: function getPublicKeyList(datastore_ctx) {
     const escaped_public_keys = [];
     for (let dk of datastore_ctx.app_public_keys) {
        escaped_public_keys.push(escape(dk.public_key));
     }
     const res = escaped_public_keys.join(',');
     return res;
  }
docs: /*
  Get query string public key list from datastore context