How to use the pg-promise.as.ctf function in pg-promise

schema, // replaces ${schema~} with the value of the `schema` argument
    },
  };

  const queryFile: QueryFile = new QueryFile(fullPath, options);

  if (queryFile.error) {
    // Something is wrong with our query file :(
    // Testing all files through queries can be cumbersome,
    // so we also report it here, while loading the module:
    // tslint:disable-next-line:no-console
    console.error(queryFile.error);
  }

  // @ts-ignore
  return queryFile[as.ctf.toPostgres]();
}