multilevel_array(size_t head_bits, size_t array_bits )
: m_Metrics(feldman_hashset::details::metrics::make( head_bits, array_bits, c_hash_size ))
, m_Head( alloc_head_node())
multilevel_array(size_t head_bits, size_t array_bits )
: m_Metrics(feldman_hashset::details::metrics::make( head_bits, array_bits, c_hash_size ))
, m_Head( alloc_head_node())