Replace explicit z-level checks with defines

code/modules/power/singularity/narsie.dm

@@ -61,7 +61,7 @@
 			var/mob/living/L = cult_mind.current
 			L.narsie_act()
 	for(var/mob/living/player in GLOB.player_list)
-		if(player.stat != DEAD && (player.loc.z in GLOB.station_z_levels) && !iscultist(player))
+		if(player.stat != DEAD && is_station_level(player.loc.z) && !iscultist(player))
 			souls_needed[player] = TRUE
 	soul_goal = round(1 + LAZYLEN(souls_needed) * 0.6)
 	INVOKE_ASYNC(src, .proc/begin_the_end)