/// Returns the maximum possible number of elements size_type max_size() const { return partition_vector_.max_size(); }
size_type max_size() const { return data_.max_size(); }
/// Returns the maximum possible number of elements size_type max_size() const { return partition_unordered_map_.max_size(); }
size_type max_size() const noexcept { return data_.max_size(); }