diff --git a/togglekey.h b/togglekey.h
index 294b4d1..b959476 100644
--- a/togglekey.h
+++ b/togglekey.h
@@ -1 +1,10 @@
+/* 
+Run cage to obtain key codes:
+$ XTMAPPER_WIDTH=100 XTMAPPER_HEIGHT=100 ./build/cage sh
+Output:
+/dev/input/wl_keyboard: EV_KEY KEY_D DOWN
+/dev/input/wl_keyboard: EV_KEY KEY_W UP
+/dev/input/wl_keyboard: EV_KEY KEY_F11 DOWN
+/dev/input/wl_keyboard: EV_KEY KEY_SUPER_L UP
+*/
 #define TOGGLEKEY "KEY_F11"