This is the code that copilot nearly entirely auto-generates for a function called `finetune` and a 1-line docstring

copilot_torch.py

# I added all the imports by hand
import torch
from torchvision.datasets import ImageFolder
from torchvision import transforms,models
from torch import nn,optim

# For all functions including this one, I wrote the name and docstring, and sometimes also the param names
def finetune(folder, model):
    """fine tune pytorch model using images from folder and report results on validation set"""
    if not os.path.exists(folder): raise ValueError(f"{folder} does not exist")
    if not os.path.exists(model): raise ValueError(f"{model} does not exist")
    if not os.path.exists(f'{folder}/val'): raise ValueError(f"{folder}/val does not exist")
    if not os.path.exists(f'{folder}/train'): raise ValueError(f"{folder}/train does not exist")

    # build model
    model = getattr(models,model)()
    model.load_state_dict(torch.load(model))
    model = model.to(device)

    # load data
    train_set = ImageFolder(folder,'train',transform=data_transforms['train'])
    val_set = ImageFolder(folder,'val',transform=data_transforms['val'])
    train_loader = torch.utils.data.DataLoader(train_set,batch_size=4,shuffle=True,num_workers=2)
    val_loader = torch.utils.data.DataLoader(val_set,batch_size=4,shuffle=True,num_workers=2)

    # fine-tune
    criterion = nn.CrossEntropyLoss()
    optimizer = optim.SGD(model.parameters(),lr=0.001,momentum=0.9)
    for epoch in range(1,10):
        train(model,train_loader,criterion,optimizer,log_interval=100)
        validate(model,val_loader,criterion)

    # save model
    torch.save(model.state_dict(),model)

# `data_transforms` and `device` are both used above but not defined, so I told copilot to define them
# I had to type "data_transforms =" to get copilot to fill out the definition
data_transforms = {
    'train': transforms.Compose([
        transforms.RandomResizedCrop(224),
        transforms.RandomHorizontalFlip(),
        transforms.ToTensor(),
        transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225])
    ]),
    'val': transforms.Compose([
        transforms.Resize(256),
        transforms.CenterCrop(224),
        transforms.ToTensor(),
        transforms.Normalize([0.485, 0.456, 0.406], [0.229, 0.224, 0.225])
    ])
}

# I had to type "device =" to get copilot to fill out the definition
device = torch.device("cuda:0" if torch.cuda.is_available() else "cpu")
        
# I had to type "def train(" to get copilot to fill out the definition
# NB: this function doesn't quite work, since it uses `epoch`, but that didn't get passed in
def train(model, train_loader, criterion, optimizer, log_interval=100):
    "train model"
    model.train()
    for batch_idx, (data, target) in enumerate(train_loader):
        data, target = data.to(device), target.to(device)
        optimizer.zero_grad()
        output = model(data)
        loss = criterion(output, target)
        loss.backward()
        optimizer.step()
        if batch_idx % log_interval == 0:
            print('Train Epoch: {} [{}/{} ({:.0f}%)]\tLoss: {:.6f}'.format(
                epoch, batch_idx * len(data), len(train_loader.dataset),
                100. * batch_idx / len(train_loader), loss.item()))

# I had to type "def validate(" to get copilot to fill out the definition
def validate(model, val_loader, criterion):
    "validate model"
    model.eval()
    val_loss = 0
    correct = 0
    with torch.no_grad():
        for data, target in val_loader:
            data, target = data.to(device), target.to(device)
            output = model(data)
            val_loss += criterion(output, target).item()
            pred = output.max(1, keepdim=True)[1]
            correct += pred.eq(target.view_as(pred)).sum().item()
    val_loss /= len(val_loader.dataset)
    print('\nValidation set: Average loss: {:.4f}, Accuracy: {}/{} ({:.0f}%)\n'.format(
        val_loss, correct, len(val_loader.dataset),
        100. * correct / len(val_loader.dataset)))