message: get mean to query easily a stake pool id
diff: @@ -135,9 +135,18 @@ impl Header {
  HeaderHash::hash_bytes(&bytes[..])
  }
  + #[inline]
  pub fn proof(&self) -> &Proof {
  &self.proof
  }
  +
  + #[inline]
  + pub fn get_stakepool_id(&self) -> Option<&StakePoolId> {
  + match self.proof() {
  + Proof::GenesisPraos(proof) => Some(&proof.node_id),
  + _ => None,
  + }
  + }
  }
  impl property::ChainLength for ChainLength {
  