function psi\fseek(object $stream, int $offset, int $whence) : int {
let stream = objval($stream);
let offset = intval($offset);
let whence = intval($whence);
function psi\fseek(object $stream, int $offset, int $whence) : int {
let stream = objval($stream);
let offset = intval($offset);
let whence = intval($whence);