message: Add some more explanatory comments.
diff: @@ -372,6 +372,11 @@ where
  |(maybe_block, fs)| Event::IsBondedFutureEra(maybe_block, fs),
  ),
  Event::IsBondedFutureEra(maybe_block, fs) => {
  + // This should be safe to do. `self.latest_block` will be None only if ew haven't
  + // finalized *any* block yet. which will be just after the Genesis
  + // era start. Even if we receive a finality signature before finalizing anything,
  + // that will be for the *current* era and we won't be looking up whether validator
  + // is bonded in the Contract Runtime.
  let state_root_hash = self
  .latest_block
  .as_ref()
  @@ -382,7 +387,7 @@ where
  .as_ref()
  .map(|lb| lb.header().era_id().successor())
  .unwrap();
  - // TODO:
  + // TODO: Use protocol version that is valid for the block's height.
  let protocol_version = ProtocolVersion::new(SemVer::V1_0_0);
  effect_builder
  .is_bonded_in_future_era(
  @@ -415,8 +420,9 @@ where
  effects
  }
  Some(_block) if !is_bonded => {
  - // Known block but not a valid validator.
  - // Validator cannot be from the future era b/c we wouldn't have the block.
  + // Known block but not a bonded validator (neither in current nor in future
  + // era). Validator cannot be from the future era b/c
  + // we wouldn't have the block.
  let FinalitySignature {
  public_key,
  block_hash,
  @@ -432,25 +438,15 @@ where
  }
  None if is_bonded => {
  // Unknown block but validator is bonded.
  - let block_hash = fs.block_hash;
  - let signers = self
  - .pending_finality_signatures
  - .values()
  - .filter_map(|sigs| sigs.get(&block_hash))
  - .map(|fs| format!("{}", fs.public_key))
  - .collect_vec();
  - if !signers.is_empty() {
  - // We have signatures for an unknown block. Print log messages.
  - warn!(
  - %block_hash, signers = %signers.join(", "),
  - "received signatures for a block that was not found in storage"
  - )
  - }
  + // We should finalize the same block eventually. Either in this or in the
  + // next era.
  + self.add_finality_signature(*fs);
  Effects::new()
  }
  None if !is_bonded => {
  // Unknown block from unknown validator.
  - // TODO: Check if validator will be bonded in the next era.
  + // We don't have the block in storage and validator is not bonded in this
  + // era or in the next one.
  let FinalitySignature {
  public_key,
  block_hash,
  @@ -461,7 +457,7 @@ where
  %block_hash,
  "Received a signature from a validator that is not bonded."
  );
  - self.add_finality_signature(*fs);
  + // TODO: Disconnect from the sender.
  Effects::new()
  }
  other => {
  