Function sp_consensus_subspace::digests::extract_pre_digest

pub fn extract_pre_digest<Header>(
    header: &Header,
) -> Result<PreDigest<FarmerPublicKey, FarmerPublicKey>, Error>
where
    Header: HeaderT,

Extract the Subspace pre digest from the given header. Pre-runtime digests are mandatory, the function will return Err if none is found.