Update tutorials (#463)

---------

Co-authored-by: Dario Coscia <93731561+dario-coscia@users.noreply.github.com>

pina/label_tensor.py

@@ -479,10 +479,9 @@ class LabelTensor(torch.Tensor):
 
         # Retrieve selected tensor and labels
         selected_tensor = super().__getitem__(index)
-        if hasattr(self, "_labels"):
-            original_labels=self._labels
-        else:
+        if not hasattr(self, "_labels"):
             return selected_tensor
+
         original_labels = self._labels
         updated_labels = copy(original_labels)
 

pina/model/block/convolution_2d.py

@@ -500,7 +500,6 @@ class ContinuousConvBlock(BaseContinuousConv):
 
         # initialize grid
         X = self._grid_transpose.clone().detach()
-        
         conv_transposed = self._grid_transpose.clone().detach()
 
         # list to iterate for calculating nn output