Return FALSE

code/game/machinery/cryo.dm

@@ -143,7 +143,6 @@
 	if(..() || usr == occupant)
 		return TRUE
 
-	. = TRUE
 	switch(action)
 		if("switchOn")
 			on = 1
@@ -158,12 +157,13 @@
 				update_icon()
 		if("ejectOccupant")
 			if(!occupant || isslime(usr) || ispAI(usr))
-				return 0 // don't update UIs attached to this object
+				return FALSE // don't update UIs attached to this object
 			go_out()
 		else
 			return FALSE
 
 	add_fingerprint(usr)
+	return TRUE
 
 /obj/machinery/atmospherics/unary/cryo_cell/attackby(var/obj/item/weapon/G as obj, var/mob/user as mob)
 	if(istype(G, /obj/item/weapon/reagent_containers/glass))

code/modules/surgery/implant.dm

@@ -120,7 +120,7 @@
 
 /datum/surgery_step/cavity/place_item/can_use(mob/living/user, mob/living/carbon/human/target, target_zone, obj/item/tool)
 	if(!istype(tool))
-		return 0
+		return FALSE
 	if(..())
 		var/obj/item/organ/external/affected = target.get_organ(target_zone)
 		if(istype(user,/mob/living/silicon/robot))

code/modules/surgery/limb_reattach.dm

@@ -29,7 +29,7 @@
 
 /datum/surgery_step/limb/attach/can_use(mob/living/user, mob/living/carbon/human/target, target_zone, obj/item/tool)
 	if(!istype(tool))
-		return 0
+		return FALSE
 	var/obj/item/organ/external/E = tool
 	var/obj/item/organ/external/P = target.organs_by_name[E.parent_organ]
 	var/obj/item/organ/external/affected = target.get_organ(target_zone)

code/modules/surgery/organs_internal.dm

@@ -165,7 +165,7 @@
 		return 0
 
 	if(!istype(tool))
-		return 0
+		return FALSE
 
 	var/obj/item/organ/external/affected = target.get_organ(target_zone)
 
@@ -231,7 +231,7 @@
 		return 0
 
 	if(!istype(tool))
-		return 0
+		return FALSE
 
 	target.op_stage.current_organ = null
 
@@ -368,7 +368,7 @@
 		return 0
 
 	if(!istype(tool))
-		return 0
+		return FALSE
 
 	target.op_stage.current_organ = null
 
@@ -427,7 +427,7 @@
 		return 0
 
 	if(!istype(tool))
-		return 0
+		return FALSE
 
 	target.op_stage.current_organ = null