Python name 'device' is not defined

The error message "Python name 'device' is not defined" means that the variable "device" has not been defined or declared before it is being used in the code.

To fix this error, you need to declare or define the "device" variable before using it. You can define it using the "torch.device" method, which is commonly used in PyTorch code.

Here's an example code snippet that defines the "device" variable:

import torch

# define device
device = torch.device("cuda" if torch.cuda.is_available() else "cpu")

# use device in code
model.to(device)

In this example, we are using the "torch.cuda.is_available()" method to check if a GPU is available and then defining the "device" variable accordingly. We can then use this variable in our code to move the model to the GPU using the "to()" method.