cxx20ranges

#include <version>
#ifdef __cpp_lib_ranges
  #include<ranges>
  namespace sr = std::ranges;
  namespace sv = std::views;
#elif __has_include (<range/v3/all.hpp>)
  #include<range/v3/all.hpp>
  namespace sr = ranges;
  namespace sv = ranges::views;
  #warning Using rangesv3 3rd party library
#else
#error No suitable header for C++20 ranges was found!
#endif