type PtyError … func ptyError(name string, err error) *PtyError { … } func (e *PtyError) Error() string { … } func (e *PtyError) Unwrap() error { … } var ErrNotSupported … // Open returns a control pty and the name of the linked process tty. // // If Open is not implemented on this platform, it returns ErrNotSupported. func Open() (pty *os.File, processTTY string, err error) { … }