Fix add tensor

csrc/tensor.cpp

@@ -209,7 +209,7 @@ extern "C" {
         }
 
         if (strcmp(tensor1->device, tensor2->device) != 0) {
-            fprintf(stderr, "Tensors must be on the same device\n");
+            fprintf(stderr, "Tensors must be on the same device: %s and %s\n", &tensor1->device, &tensor2->device);
             exit(1);
         }
 

norch/tensor.py

@@ -84,6 +84,8 @@ class Tensor:
         Tensor._C.to_device.restype = None
         Tensor._C.to_device(self.tensor, self.device_ctype)
 
+        return self
+
     def __getitem__(self, indices):
         if len(indices) != self.ndim:
             raise ValueError("Number of indices must match the number of dimensions")