diff -r 52e10e8d88cc -r 1a4342d80de7 src/main.h
--- a/src/main.h	Wed Jun 08 19:33:00 2022 +0300
+++ b/src/main.h	Wed Jun 08 20:41:21 2022 +0300
@@ -265,6 +265,9 @@
 	}
 }
 
+template<typename T>
+using opt = std::optional<T>;
+
 // some magic code from https://en.cppreference.com/w/cpp/utility/variant/visit
 // for use with std::visit
 template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };