message: add a function to check if the header is a genesis header or not.
diff: @@ -87,6 +87,10 @@ impl BlockHeader {
  match self {
  &BlockHeader::GenesisBlockHeader(ref blo) => SlotId { epoch: blo.consensus.epoch, slotid: 0 },
  &BlockHeader::MainBlockHeader(ref blo) => blo.consensus.slot_id.clone(),
  + pub fn is_genesis_block(&self) -> bool {
  + match self {
  + &BlockHeader::GenesisBlockHeader(_) => true,
  + &BlockHeader::MainBlockHeader(_) => false,
  }
  }
  