why does batch have batch[0]、batch[1].......

[sunyclj]

I don't understand this part of the test code，I think testing_data_loader is the test set data，only one image ,Why does batch have a lot of data，such as batch[0]、batch[1].......
code:
for batch in testing_data_loader:
#import pdb;pdb.set_trace()
input, target, neigbor, flow, bicubic = batch[0], batch[1], batch[2], batch[3], batch[4]
with torch.no_grad():
if cuda:
input = Variable(input).cuda(gpus_list[0])
bicubic = Variable(bicubic).cuda(gpus_list[0])
neigbor = [Variable(j).cuda(gpus_list[0]) for j in neigbor]
flow = [Variable(j).cuda(gpus_list[0]).float() for j in flow]
else:
input = Variable(input).to(device=device, dtype=torch.float)
bicubic = Variable(bicubic).to(device=device, dtype=torch.float)
neigbor = [Variable(j).to(device=device, dtype=torch.float) for j in neigbor]
flow = [Variable(j).to(device=device, dtype=torch.float) for j in flow]