diff --git a/src/TensorFlowNET.Keras/Engine/BasePreprocessingLayer.cs b/src/TensorFlowNET.Keras/Engine/BasePreprocessingLayer.cs
index 6beda9fe..61c57d39 100644
--- a/src/TensorFlowNET.Keras/Engine/BasePreprocessingLayer.cs
+++ b/src/TensorFlowNET.Keras/Engine/BasePreprocessingLayer.cs
@@ -1,10 +1,58 @@
-using System;
+using Keras.Layers;
+using NumSharp;
+using System;
 using System.Collections.Generic;
 using System.Text;
+using Tensorflow.Data;
+using Tensorflow.Keras.Initializers;
 
 namespace Tensorflow.Keras.Engine
 {
-    class BasePreprocessingLayer
+    public abstract class PreprocessingLayer : Layer
     {
+        public abstract void adapt(Data.DatasetV1 data, bool reset_state = true);
+    }
+
+    public abstract class Combiner
+    {
+        public abstract dynamic compute(NDArray[] batch_values, dynamic accumulator = null);
+
+        public abstract dynamic merge(dynamic[] accumulators);
+
+        public abstract NDArray[] extract(dynamic accumulator);
+
+        public abstract dynamic restore(Tensor output);
+
+        public abstract string serialize(dynamic accumulator);
+
+        public abstract dynamic deserialize(string encoded_accumulator);
+
+        public override string ToString()
+        {
+            throw new NotImplementedException();
+        }
+    }
+
+    public class CombinerPreprocessingLayer : PreprocessingLayer
+    {
+        public CombinerPreprocessingLayer(Combiner combiner)
+        {
+            throw new NotImplementedException();
+        }
+
+        private void _add_state_variable(string name, TensorShape shape, string dtype, Initializer initializer= null, string partitioner= null, bool? use_resource= null) => throw new NotImplementedException();
+
+        private Dictionary<string, NDArray> _restore_updates() => throw new NotImplementedException();
+
+        private bool _dataset_is_infinite(DatasetV1 dataset) => throw new NotImplementedException();
+
+        private dynamic _get_dataset_iterator(DatasetV1 dataset) => throw new NotImplementedException();
+
+        private void _set_state_variables(Dictionary<string, Tensor> updates) => throw new NotImplementedException();
+
+        public override void adapt(DatasetV1 data, bool reset_state = true)
+        {
+            throw new NotImplementedException();
+        }
     }
 }
diff --git a/src/TensorFlowNET.Keras/Engine/CallContext.cs b/src/TensorFlowNET.Keras/Engine/CallContext.cs
index 0b3c5ff2..5547c6de 100644
--- a/src/TensorFlowNET.Keras/Engine/CallContext.cs
+++ b/src/TensorFlowNET.Keras/Engine/CallContext.cs
@@ -1,10 +1,45 @@
-using System;
+using Keras.Layers;
+using System;
 using System.Collections.Generic;
+using System.Reflection;
 using System.Text;
 
 namespace Tensorflow.Keras.Engine
 {
     public class CallContext
     {
+        public bool in_keras_graph
+        {
+            get
+            {
+                throw new NotImplementedException();
+            }
+        }
+        public CallContext()
+        {
+
+        }
+
+        public void enter(Layer layer, Tensor[] inputs, Graph build_graph, bool training, Saving saving = null) => throw new NotImplementedException();
+
+        public bool training_arg_passed_to_call(string[] argspec, Dictionary<string, object> args, Dictionary<string, object>  kwargs) => throw new NotImplementedException();
+
+        public dynamic autocast_context_manager(string dtype) => throw new NotImplementedException();
+
+        public bool is_subclassed(Layer layer) => throw new NotImplementedException();
+
+        public bool from_saved_model(Layer layer) => throw new NotImplementedException();
+
+        public bool check_graph_consistency(Tensor tensor = null, string method = "add_loss", bool force_raise = false) => throw new NotImplementedException();
+
+        public dynamic mark_as_return(Tensor[] outputs, dynamic acd) => throw new NotImplementedException();
+
+        public MethodInfo Default(MemberInfo method) => throw new NotImplementedException();
+
+        public void enable_v2_dtype_behavior() => throw new NotImplementedException();
+
+        public void disable_v2_dtype_behavior() => throw new NotImplementedException();
+
+        public void v2_dtype_behavior_enabled() => throw new NotImplementedException();
     }
 }
diff --git a/src/TensorFlowNET.Keras/Engine/Saving.cs b/src/TensorFlowNET.Keras/Engine/Saving.cs
index 43ba2cf6..8ba804c3 100644
--- a/src/TensorFlowNET.Keras/Engine/Saving.cs
+++ b/src/TensorFlowNET.Keras/Engine/Saving.cs
@@ -4,7 +4,7 @@ using System.Text;
 
 namespace Tensorflow.Keras.Engine
 {
-    class Saving
+    public class Saving
     {
     }
 }
diff --git a/src/TensorFlowNET.Keras/Engine/TrackableWeightHandler.cs b/src/TensorFlowNET.Keras/Engine/TrackableWeightHandler.cs
new file mode 100644
index 00000000..c6305809
--- /dev/null
+++ b/src/TensorFlowNET.Keras/Engine/TrackableWeightHandler.cs
@@ -0,0 +1,26 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Tensorflow.Keras.Engine
+{
+    public class TrackableWeightHandler
+    {
+        public int num_tensors
+        {
+            get
+            {
+                throw new NotImplementedException();
+            }
+        }
+
+        public TrackableWeightHandler(bool trackable)
+        {
+            throw new NotImplementedException();
+        }
+
+        public void set_weights(Tensor[] weights) => throw new NotImplementedException();
+
+        public void _set_weights_v1(Tensor[] weights) => throw new NotImplementedException();
+    }
+}