copy value when get numpy.

src/TensorFlowNET.Core/NumPy/AutoNumPyAttribute.cs

@@ -1,6 +1,7 @@
 using MethodBoundaryAspect.Fody.Attributes;
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using Tensorflow.Eager;
 using Tensorflow.Functions;
@@ -8,6 +9,7 @@ using static Tensorflow.Binding;
 
 namespace Tensorflow.NumPy
 {
+    [DebuggerStepThrough]
     public sealed class AutoNumPyAttribute : OnMethodBoundaryAspect
     {
         bool _changedMode = false;

src/TensorFlowNET.Core/NumPy/NumPy.Sorting.Searching.Counting.cs

@@ -10,7 +10,7 @@ namespace Tensorflow.NumPy
     {
         [AutoNumPy]
         public static NDArray argmax(NDArray a, Axis axis = null)
-            => new NDArray(math_ops.argmax(a, axis));
+            => new NDArray(math_ops.argmax(a, axis ?? 0));
 
         [AutoNumPy]
         public static NDArray argsort(NDArray a, Axis axis = null)

src/TensorFlowNET.Core/Numpy/NDArray.Creation.cs

@@ -31,7 +31,7 @@ namespace Tensorflow.NumPy
         public NDArray(IntPtr address, Shape shape, TF_DataType dtype) 
             : base(address, shape, dtype) { NewEagerTensorHandle(); }
 
-        public NDArray(Tensor tensor, bool eval = true) : base(tensor.Handle) 
+        public NDArray(Tensor tensor, bool clone = false) : base(tensor.Handle, clone: clone) 
         {
             if (_handle is null)
             {

src/TensorFlowNET.Core/Operations/Operation.Input.cs

@@ -35,7 +35,7 @@ namespace Tensorflow
             tf.Status.Check(true);
             return num;
         }
-        public int NumInputs => c_api.TF_OperationNumInputs(_handle);
+        public int NumInputs => _handle == IntPtr.Zero ? -1 : c_api.TF_OperationNumInputs(_handle);
         private TF_DataType[] _input_types => _inputs_val._inputs.Select(x => x.dtype).ToArray();
 
         protected InputList _inputs_val;

src/TensorFlowNET.Core/Operations/Operation.Output.cs

@@ -23,7 +23,7 @@ namespace Tensorflow
 {
     public partial class Operation
     {
-        public int NumOutputs => c_api.TF_OperationNumOutputs(_handle);
+        public int NumOutputs => _handle == IntPtr.Zero ? -1 : c_api.TF_OperationNumOutputs(_handle);
         public TF_DataType OutputType(int index) => c_api.TF_OperationOutputType(_tf_output(index));
 
         public int OutputListLength(string name)
@@ -38,7 +38,7 @@ namespace Tensorflow
         public virtual Tensor[] outputs => _outputs;
         public Tensor output => _outputs.FirstOrDefault();
 
-        public int NumControlOutputs => c_api.TF_OperationNumControlOutputs(_handle);
+        public int NumControlOutputs => _handle == IntPtr.Zero ? -1 : c_api.TF_OperationNumControlOutputs(_handle);
 
         public int OutputNumConsumers(int index) => c_api.TF_OperationOutputNumConsumers(new TF_Output(_handle, index));
 

src/TensorFlowNET.Core/Tensors/Tensor.Creation.cs

@@ -39,9 +39,12 @@ namespace Tensorflow
         ///     Create a Tensor object from an existing TF handle
         /// </summary>
         /// <param name="handle">Handle to a <see cref="Tensor"/> object.</param>
-        public Tensor(SafeTensorHandle handle)
+        public unsafe Tensor(SafeTensorHandle handle, bool clone = false)
         {
             _handle = handle;
+            if (clone)
+                _handle = TF_NewTensor(shape, dtype, data: TensorDataPointer.ToPointer());
+                
             isCreatedInGraphMode = !tf.executing_eagerly();
         }
 

src/TensorFlowNET.Core/Tensors/Tensor.Value.cs

@@ -55,7 +55,7 @@ namespace Tensorflow
                 return new NDArray(str, shape);
             }
                 
-            return new NDArray(this);
+            return new NDArray(this, clone: true);
         }
 
         /// <summary>