maybe a simpler unique_ptr

lib/include/aocpp/Startup.hpp

@@ -8,17 +8,7 @@
 
 namespace aocpp {
 
-class ConditionalDeleter {
-  bool should_delete_;
-
-public:
-  ConditionalDeleter(bool should_delete) : should_delete_ {should_delete} {}
-  
-  template <typename T>
-  auto operator()(T * pointer) -> void { if (should_delete_) { delete pointer; }}
-};
-
-auto Startup(int argc, char ** argv) -> std::unique_ptr<std::istream, ConditionalDeleter>;
+auto Startup(int argc, char ** argv) -> std::unique_ptr<std::istream, void(*)(std::istream*)>;
 
 }