class WebService {
void setPassword(ValidPassword password, Confirm!"password" password_confirmation)
{
// password is valid and guaranteed to equal password_confirmation
}
void setProfileInfo(string full_name, Nullable!ValidPassword password, Nullable!(Confirm!"password") password_confirmation)
{
// Password is valid and guaranteed to equal password_confirmation
// It is allowed for both, password and password_confirmation
// to be absent at the same time, but not for only one of them.
}
}