Optimize a couple things

code/modules/instruments/instrument_data/_instrument_data.dm

@@ -70,8 +70,7 @@
 
 /datum/instrument/Destroy()
 	SSinstruments.instrument_data -= id
-	for(var/i in songs_using)
-		var/datum/song/S = i
+	for(var/datum/song/S as anything in songs_using)
 		S.set_instrument(null)
 	real_samples = null
 	samples = null

code/modules/instruments/items.dm

@@ -296,8 +296,7 @@
 							/obj/item/instrument/harmonica,
 							/obj/item/instrument/piano_synth/headphones
 							)
-		for(var/V in templist)
-			var/atom/A = V
+		for(var/atom/A as anything in templist)
 			instruments[initial(A.name)] = A
 	return instruments
 */

code/modules/instruments/songs/play_legacy.dm

@@ -80,8 +80,7 @@
 	if((world.time - MUSICIAN_HEARCHECK_MINDELAY) > last_hearcheck)
 		do_hearcheck()
 	var/sound/music_played = sound(soundfile)
-	for(var/i in hearing_mobs)
-		var/mob/M = i
+	for(var/mob/M as anything in hearing_mobs)
 		/* Would be nice
 		if(user && HAS_TRAIT(user, TRAIT_MUSICIAN) && isliving(M))
 			var/mob/living/L = M

code/modules/instruments/songs/play_synthesized.dm

@@ -61,8 +61,7 @@
 	channels_playing[channel_text] = 100
 	last_channel_played = channel_text
 	var/turf/source = get_turf(parent)
-	for(var/i in hearing_mobs)
-		var/mob/M = i
+	for(var/mob/M as anything in hearing_mobs)
 		/* Maybe someday
 		if(user && HAS_TRAIT(user, TRAIT_MUSICIAN) && isliving(M))
 			var/mob/living/L = M
@@ -142,10 +141,8 @@
 		if(dead)
 			channels_playing -= channel
 			channels_idle += channel
-			for(var/i in hearing_mobs)
-				var/mob/M = i
+			for(var/mob/M as anything in hearing_mobs)
 				M.stop_sound_channel(channelnumber)
 		else
-			for(var/i in hearing_mobs)
-				var/mob/M = i
+			for(var/mob/M as anything in hearing_mobs)
 				M.set_sound_channel_volume(channelnumber, (current_volume * 0.01) * volume * using_instrument.volume_multiplier)