what does

running_loss
in this code ? i know it calculated the loss , and we need to get the probability .
please take a look at the comment sections
for e in range(epochs):
running_loss = 0
for images, labels in trainloader:
# this loop through 938 images and labels (length of trainloader
images = images.view(images.shape[0], -1)

    optimizer.zero_grad()
    
    output = model.forward(images)
    loss = criterion(output, labels)
    loss.backward()
    optimizer.step()
    
    running_loss += loss.item() #what this line does
else:
    print(f"Training loss: {running_loss/len(trainloader)}")  

thanks