diff --git a/Example_Aramakme_License/example_lib.mo b/Example_Aramakme_License/example_lib.mo
index 9bc69a6..dc32531 100644
--- a/Example_Aramakme_License/example_lib.mo
+++ b/Example_Aramakme_License/example_lib.mo
@@ -243,6 +243,7 @@ module {
 
     public type UpdateMode = {
         #Set    : CandyValue;
+        #Lock   : CandyValue;
         #Next   : [Update];
     };
 
diff --git a/dfx.json b/dfx.json
index 8b7b8fe..4d4a0df 100644
--- a/dfx.json
+++ b/dfx.json
@@ -12,7 +12,7 @@
       "packtool": "vessel sources"
     }
   },
-  "dfx": "0.9.2",
+  "dfx": "0.9.3",
   "networks": {
     "local": {
       "bind": "127.0.0.1:8000",
diff --git a/src/conversion.mo b/src/conversion.mo
index e5534b7..c92e460 100644
--- a/src/conversion.mo
+++ b/src/conversion.mo
@@ -1124,6 +1124,22 @@ module {
             return textToByteBuffer(_text).toArray();
         };
 
+        public func textToNat(phrase : Text) : ?Nat {
+            var theSum : Nat = 0;
+            Iter.iterate(Text.toIter(phrase), func (x : Char, n : Nat){
+                //todo: check for digits
+                theSum := theSum + ((Nat32.toNat(Char.toNat32(x)) - 48) * 10 **  (phrase.size()-n-1));
+            });
+            return ?theSum;
+        };
+
+        public func valueToProperties(val : CandyValue) : Types.Properties {
+            switch(val){
+                case(#Class(val)){ val};
+                case(_){assert(false);/*unreachable*/[];};
+            };
+        };
+
         public func bytesToText(_bytes : [Nat8]) : Text{
             
             var result : Text = "";
@@ -1182,8 +1198,10 @@ module {
                 bytes := List.push<Nat8>(a, bytes);
                 test := b > 0;
             };
-
-            Array.append<Nat8>([c],List.toArray<Nat8>(bytes));
+            let result = toBuffer<Nat8>([c]);
+            result.append(toBuffer<Nat8>(List.toArray<Nat8>(bytes)));
+            result.toArray();
+            //Array.append<Nat8>([c],List.toArray<Nat8>(bytes));
         };
 
         public func bytesToInt(_bytes : [Nat8]) : Int{
diff --git a/src/properties.mo b/src/properties.mo
index 8c10e7e..d762474 100644
--- a/src/properties.mo
+++ b/src/properties.mo
@@ -38,12 +38,11 @@ module {
         };
 
         private func fromPropertyUnstableMap(m : HashMap.HashMap<Text,PropertyUnstable>) : PropertiesUnstable {
-            
-            var ps : PropertiesUnstable = [];
+            var ps : Buffer.Buffer<PropertyUnstable> = Buffer.Buffer<PropertyUnstable>(m.size());
             for ((_, p) in m.entries()) {
-                ps := Array.append(ps, [p]);
+                ps.add(p);
             };
-            ps;
+            ps.toArray();
         };
 
 
@@ -51,7 +50,7 @@ module {
         // NOTE: ignores unknown properties.
         public func getPropertiesUnstable(properties : PropertiesUnstable, qs : [Query]) : Result.Result<PropertiesUnstable, PropertyError> {
             let m               = toPropertyUnstableMap(properties);
-            var ps : PropertiesUnstable = [];
+            var ps : Buffer.Buffer<PropertyUnstable> = Buffer.Buffer<PropertyUnstable>(m.size());
             for (q in qs.vals()) {
                 switch (m.get(q.name)) {
                     case (null) {
@@ -63,18 +62,18 @@ module {
                             case (#Class(c)) {
                                 if (q.next.size() == 0) {
                                     // Return every sub-attribute attribute.
-                                    ps := Array.append(ps, [p]);
+                                    ps.add(p);
                                 } else {
                                     let sps = switch (getPropertiesUnstable(c, q.next)) {
                                         case (#err(e)) { return #err(e); };
                                         case (#ok(v))  { v; };
                                     };
                                     
-                                    ps := Array.append(ps, [{
+                                    ps.add({
                                         name      = p.name;
                                         value     = #Class(sps);
                                         immutable = p.immutable;
-                                    }]);
+                                    });
                                 };
                             };
                             case (other) {
@@ -82,13 +81,13 @@ module {
                                 if (q.next.size() != 0) {
                                     return #err(#NotFound);
                                 };
-                                ps := Array.append(ps, [p]);
+                                ps.add(p);
                             };
                         }
                     };
                 };
             };
-            #ok(ps);
+            #ok(ps.toArray());
         };
 
         // Updates the given properties based on the given update query.
@@ -119,6 +118,13 @@ module {
                                     immutable = false;
                                 });
                             };
+                            case (#Lock(v)) {
+                                m.put(u.name, {
+                                    name      = u.name;
+                                    value     = v;
+                                    immutable = true;
+                                });
+                            };
                         };
                     };
                     case (? p)  {
@@ -155,6 +161,13 @@ module {
                                     immutable = false;
                                 });
                             };
+                            case (#Lock(v)) {
+                                m.put(u.name, {
+                                    name      = p.name;
+                                    value     = v;
+                                    immutable = true;
+                                });
+                            };
                         };
                     };
                 };
@@ -212,18 +225,18 @@ module {
 
         private func fromPropertyMap(m : HashMap.HashMap<Text,Property>) : Properties {
             
-            var ps : Properties = [];
+            var ps : Buffer.Buffer<Property> = Buffer.Buffer(m.size());
             for ((_, p) in m.entries()) {
-                ps := Array.append(ps, [p]);
+                ps.add(p);
             };
-            ps;
+            ps.toArray();
         };
 
         // Returns a subset of from properties based on the given query.
         // NOTE: ignores unknown properties.
         public func getProperties(properties : Properties, qs : [Query]) : Result.Result<Properties, PropertyError> {
             let m               = toPropertyMap(properties);
-            var ps : Properties = [];
+            var ps : Buffer.Buffer<Property> = Buffer.Buffer<Property>(m.size());
             for (q in qs.vals()) {
                 switch (m.get(q.name)) {
                     case (null) {
@@ -236,18 +249,18 @@ module {
                             case (#Class(c)) {
                                 if (q.next.size() == 0) {
                                     // Return every sub-attribute attribute.
-                                    ps := Array.append(ps, [p]);
+                                    ps.add(p);
                                 } else {
                                     let sps = switch (getProperties(c, q.next)) {
                                         case (#err(e)) { return #err(e); };
                                         case (#ok(v))  { v; };
                                     };
                                     
-                                    ps := Array.append(ps, [{
+                                    ps.add({
                                         name      = p.name;
                                         value     = #Class(sps);
                                         immutable = p.immutable;
-                                    }]);
+                                    });
                                 };
                             };
                             case (other) {
@@ -255,13 +268,13 @@ module {
                                 if (q.next.size() != 0) {
                                     return #err(#NotFound);
                                 };
-                                ps := Array.append(ps, [p]);
+                                ps.add(p);
                             };
                         }
                     };
                 };
             };
-            #ok(ps);
+            #ok(ps.toArray());
         };
 
         // Updates the given properties based on the given update query.
@@ -292,6 +305,13 @@ module {
                                     immutable = false;
                                 });
                             };
+                            case (#Lock(v)) {
+                                m.put(u.name, {
+                                    name      = u.name;
+                                    value     = v;
+                                    immutable = true;
+                                });
+                            };
                         };
                     };
                     case (? p)  {
@@ -328,6 +348,13 @@ module {
                                     immutable = false;
                                 });
                             };
+                            case (#Lock(v)) {
+                                m.put(u.name, {
+                                    name      = p.name;
+                                    value     = v;
+                                    immutable = true;
+                                });
+                            };
                         };
                     };
                 };
diff --git a/src/types.mo b/src/types.mo
index 14d06cb..10beb2a 100644
--- a/src/types.mo
+++ b/src/types.mo
@@ -30,6 +30,7 @@ module {
 
     public type UpdateModeUnstable = {
         #Set    : CandyValueUnstable;
+        #Lock    : CandyValueUnstable;
         #Next   : [UpdateUnstable];
     };
 
@@ -78,6 +79,7 @@ module {
 
     public type UpdateMode = {
         #Set    : CandyValue;
+        #Lock    : CandyValue;
         #Next   : [Update];
     };