add get_shape

hopefully got the types right here

src/TensorFlowNET.Core/Operations/Operation.cs

@@ -275,6 +275,11 @@ namespace Tensorflow
                     return NodeDef.Parser.ParseFrom(buffer.DangerousMemoryBlock.Stream());
                 }
         }
+        
+        public TensorShape get_shape(Tensor x)
+        {
+            return x.shape;
+        }
 
         /// <summary>
         /// Update the input to this operation at the given index.
@@ -323,4 +328,4 @@ namespace Tensorflow
             return new TF_Input(op, input_idx);
         }
     }
-}
+}