Function openpgp_card_sequoia::util::sign

pub fn sign(
    card_tx: &mut OpenPgpTransaction<'_>, 
    cert: &Cert, 
    input: &mut dyn Read, 
    touch_prompt: &(dyn Fn() + Send + Sync)
) -> Result<String>

FIXME: this fn is used in card_functionality, but should be removed