...one of the most highly
regarded and expertly designed C++ library projects in the
world.
— Herb Sutter and Andrei
Alexandrescu, C++
Coding Standards
The type of value when iterating.
using value_type = std::pair< string_view, string_view >;
The first element of the pair is the name, and the second element is the value which may be empty. The value is stored in its raw representation, without quotes or escapes.