pub fn use_dedicated_thread_pool(&mut self, thread_count: usize) {
        self.thread_pool = Some(Self::create_thread_pool(thread_count));
    }
Signals that the tree should use a dedicated `rayon` thread pool for parallel operations
(for now, hash computations).

If `thread_count` is 0, the default number of threads will be used; see `rayon` docs
for details.
core/lib/merkle_tree/src/domain.rs