message: [pdsl_core] Add storage::Stash::entries_key
diff: @@ -91,6 +91,16 @@ impl<T> Stash<T> {
  }
  }
  + /// Returns the unterlying key to the cells.
  + ///
  + /// # Note
  + ///
  + /// This is a low-level utility getter and should
  + /// normally not be required by users.
  + pub fn entries_key(&self) -> Key {
  + self.entries.cells_key()
  + }
  +
  /// Returns the number of elements stored in the stash.
  pub fn len(&self) -> u32 {
  *self.len.get().unwrap_or(&0)
  