Update format and typing

Signed-off-by: Beat Buesser <[email protected]>

Author: Beat Buesser

art/utils.py

@@ -36,10 +36,12 @@
 from scipy.special import gammainc
 import six
 from tqdm.auto import tqdm
-from torch import Tensor
 
 from art import config
 
+if TYPE_CHECKING:
+    import torch
+
 logger = logging.getLogger(__name__)
 
 
@@ -1241,28 +1243,30 @@ def pad_sequence_input(x: np.ndarray) -> Tuple[np.ndarray, np.ndarray]:
 # -------------------------------------------------------------------------------------------------------- CUDA SUPPORT
 
 
-def to_cuda(x: Tensor) -> Tensor:
+def to_cuda(x: "torch.Tensor") -> "torch.Tensor":
     """
     Move the tensor from the CPU to the GPU if a GPU is available.
 
     :param x: CPU Tensor to move to GPU if available.
     :return: The CPU Tensor moved to a GPU Tensor.
     """
     from torch.cuda import is_available
+
     use_cuda = is_available()
     if use_cuda:
         x = x.cuda()
     return x
 
 
-def from_cuda(x: Tensor) -> Tensor:
+def from_cuda(x: "torch.Tensor") -> "torch.Tensor":
     """
     Move the tensor from the GPU to the CPU if a GPU is available.
 
     :param x: GPU Tensor to move to CPU if available.
     :return: The GPU Tensor moved to a CPU Tensor.
     """
     from torch.cuda import is_available
+
     use_cuda = is_available()
     if use_cuda:
         x = x.cpu()