edited some functions' signature (best practices)

include/genimg/common.hh

@@ -7,8 +7,9 @@
 #include <string>
 #include <utility>
 
-std::pair<cv::Mat, cv::Mat> init_image(std::string const &);
+[[nodiscard]] std::pair<cv::Mat, cv::Mat>
+init_image(std::string const &) noexcept;
 
-double euclidian_distance(cv::Mat const &, cv::Mat const &);
+[[nodiscard]] double euclidian_distance(cv::Mat const &, cv::Mat const &);
 
 #endif /* GENETIC_IMAGE_INCLUDE_GENIMG_COMMON_HH_ */

include/genimg/parseargs.hh

@@ -4,7 +4,8 @@
 #include <filesystem>
 #include <tuple>
 
-std::tuple<std::filesystem::path, std::filesystem::path, int, int, bool>
+[[nodiscard]] std::tuple<std::filesystem::path, std::filesystem::path, int, int,
+                         bool>
 parse_args(int, char **);
 
 #endif /* GENETIC_IMAGE_INCLUDE_GENIMG_PARSEARGS_HH_ */