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Proper multiline block

Co-authored-by: Sijawusz Pur Rahnama <sija@sija.pl>

src/kemal.cr

@@ -89,10 +89,10 @@ module Kemal
   end
 
   private def self.setup_trap_signal
-    Process.on_interrupt {
+    Process.on_interrupt do
       log "#{Kemal.config.app_name} is going to take a rest!" if Kemal.config.shutdown_message
       Kemal.stop
       exit
-    }
+    end
   end
 end