fn ecdh(&self, recipient: Recipient, other_key: &PublicKey, tweak: Option<&Scalar>) -> Result<SharedSecret, ()>;
/// Sign an invoice.
+ ///
/// By parameterizing by the raw invoice bytes instead of the hash, we allow implementors of
/// this trait to parse the invoice and make sure they're signing what they expect, rather than
/// blindly signing the hash.
- /// The hrp is ascii bytes, while the invoice data is base32.
+ ///
+ /// The `hrp_bytes` are ASCII bytes, while the `invoice_data` is base32.
///
/// The secret key used to sign the invoice is dependent on the [`Recipient`].
///