http://gunnarpeipman.com/2018/01/switch-csharp-version/
origin - https://www.pipiscrew.com/2018/01/switching-c-version-in-visual-studio-2017/ switching-c-version-in-visual-studio-2017
http://gunnarpeipman.com/2018/01/switch-csharp-version/
origin - https://www.pipiscrew.com/2018/01/switching-c-version-in-visual-studio-2017/ switching-c-version-in-visual-studio-2017