message: assume that we can unwrap here.
  The only reason this would fail is if the cbor `Serialiazer` would not
  be able to allocate more memory. If this happens, a panic is the least
  of the user's concerns.
  relates to
diff: @@ -114,7 +114,10 @@ impl cbor_event::de::Deserialize for AddrType {
  pub struct StakeholderId(DigestBlake2b224); // of publickey (block2b 256)
  impl StakeholderId {
  pub fn new(pubk: &XPub) -> StakeholderId {
  + // the reason for this unwrap is that we have to dynamically allocate 66 bytes
  + // to serialize 64 bytes in cbor (2 bytes of cbor overhead).
  let buf = cbor!(pubk).unwrap();
  +
  StakeholderId(DigestBlake2b224::new(buf.as_ref()))
  }
  }
  