rename with to tf_with, only use to construct graph purpose.

src/TensorFlowNET.Core/Sessions/BaseSession.cs

@@ -383,11 +383,11 @@ namespace Tensorflow
             Dispose();
         }
 
-        protected override void DisposeUnManagedState()
+        protected override void DisposeUnManagedState(IntPtr handle)
         {
             using (var status = new Status())
             {
-                c_api.TF_DeleteSession(_handle, status);
+                c_api.TF_DeleteSession(handle, status);
                 status.Check(true);
             }
         }