import pytorch_lightning as pl

# As an AI language model, I cannot provide a personal experience with PyTorch Lightning, but I can provide information and examples on how to use it.

PyTorch Lightning is a lightweight PyTorch wrapper for high-performance AI research. It allows researchers and practitioners to focus on the core research problem by abstracting the engineering details. PyTorch Lightning provides a high-level interface for building complex deep learning models and training pipelines. It also simplifies the process of scaling models to multiple GPUs or TPUs.

Here is an example of how to use PyTorch Lightning to train a simple neural network for image classification:

import torch
import torch.nn as nn
import torch.optim as optim
from torch.utils.data import DataLoader
from torchvision.datasets import MNIST
from torchvision.transforms import ToTensor
import pytorch_lightning as pl

class Net(nn.Module):
    def __init__(self):
        super(Net, self).__init__()
        self.conv1 = nn.Conv2d(1, 32, 3, 1)
        self.conv2 = nn.Conv2d(32, 64, 3, 1)
        self.dropout1 = nn.Dropout2d(0.25)
        self.dropout2 = nn.Dropout2d(0.5)
        self.fc1 = nn.Linear(9216, 128)
        self.fc2 = nn.Linear(128, 10)

    def forward(self, x):
        x = self.conv1(x)
        x = nn.ReLU()(x)
        x = self.conv2(x)
        x = nn.ReLU()(x)
        x = nn.MaxPool2d(2)(x)
        x = self.dropout1(x)
        x = torch.flatten(x, 1)
        x = self.fc1(x)
        x = nn.ReLU()(x)
        x = self.dropout2(x)
        x = self.fc2(x)
        output = nn.LogSoftmax(dim=1)(x)
        return output

class LitMNIST(pl.LightningModule):
    def __init__(self):
        super().__init__()
        self.net = Net()

    def forward(self, x):
        return self.net(x)

    def training_step(self, batch, batch_idx):
        x, y = batch
        y_hat = self(x)
        loss = nn.NLLLoss()(y_hat, y)
        self.log('train_loss', loss)
        return loss

    def configure_optimizers(self):
        optimizer = optim.Adam(self.parameters(), lr=1e-3)
        return optimizer

train_data = MNIST('.', train=True, download=True, transform=ToTensor())
train_loader = DataLoader(train_data, batch_size=64)

trainer = pl.Trainer(gpus=1, max_epochs=10)
model = LitMNIST()
trainer.fit(model, train_loader)

In this example, we define a simple neural network for image classification using PyTorch. We then wrap the model in a PyTorch Lightning module, which provides hooks for training and validation steps. We define a training step that calculates the loss and logs it to the PyTorch Lightning log, and we configure the optimizer to use the Adam optimizer. Finally, we create a PyTorch DataLoader for the MNIST dataset, create a PyTorch Lightning trainer with one GPU, and fit the model to the training data for 10 epochs.

Overall, PyTorch Lightning simplifies the process of training deep learning models while still allowing for flexibility and customization.