message: [pdsl_core] Add parity_codec::{Encode, Decode} impl for storage::Stash
diff: @@ -54,6 +54,23 @@ enum Entry<T> {
  Occupied(T),
  }
  +impl<T> parity_codec::Encode for Stash<T> {
  + fn encode_to<W: parity_codec::Output>(&self, dest: &mut W) {
  + self.next_vacant.encode_to(dest);
  + self.len.encode_to(dest);
  + self.entries.encode_to(dest);
  + }
  +}
  +
  +impl<T> parity_codec::Decode for Stash<T> {
  + fn decode<I: parity_codec::Input>(input: &mut I) -> Option<Self> {
  + let next_vacant = SyncCell::decode(input)?;
  + let len = SyncCell::decode(input)?;
  + let entries = SyncChunk::decode(input)?;
  + Some(Self{next_vacant, len, entries})
  + }
  +}
  +
  impl<T> Stash<T> {
  /// Creates a new storage vector for the given key.
  ///
  