message: serialization sizes notice
diff: @@ -3,7 +3,19 @@ use bigint::U256;
  use blake2::Params as Blake2Params;
  /// Maximum serialized size of the node metadata.
  -pub const MAX_NODE_DATA_SIZE: usize = 32 + 4 + 4 + 4 + 4 + 32 + 32 + 32 + 9 + 9 + 9; // 171
  +pub const MAX_NODE_DATA_SIZE: usize =
  + 32 + // subtree commitment
  + 4 + // start time
  + 4 + // end time
  + 4 + // start target
  + 4 + // end target
  + 32 + // start sapling tree root
  + 32 + // end sapling tree root
  + 32 + // subtree total work
  + 9 + // start height (compact uint)
  + 9 + // end height (compact uint)
  + 9; // shielded tx count (compact uint)
  + // = total of 171
  /// Node metadata.
  #[repr(C)]
  