 of the standard library for all cases specified in
    the ANSI/ISO C++ standard. The essence of this constraint is that
    any valid C++ program should behave in the same manner regardless
    of whether it is compiled with debug mode or release mode. In
    particular, entities that are defined in namespace std in release
    mode should remain defined in namespace std in debug mode, so that
    legal specializations of namespace std entities will remain
    valid. A program that is not valid C++ (e.g.,