Some containers may not provide proper value_type member, and the user can still manually passing its element type as Key or Data template parameter to indexing_suite. So indexing_suite already know the container's value type, and does not need containers to have ::value_type. Its detailed implementation should then directly reading it from indexing_suite, not from Container::value_type again.
see code here
Some containers may not provide proper
value_typemember, and the user can still manually passing its element type asKeyorDatatemplate parameter toindexing_suite. Soindexing_suitealready know the container's value type, and does not need containers to have::value_type. Its detailed implementation should then directly reading it fromindexing_suite, not fromContainer::value_typeagain.