def METHOD_NAME(self):
    # 1: Access the train dataloader and load a single sample.
    image, _ = self.trainer.train_dataloader.dataset[0]
    # 2: Convert the image into a PIL Image to bytes and encode it with base64
    pil_image = T.ToPILImage()(image)
    buffered = BytesIO()
    pil_image.save(buffered, format="JPEG")
    img_str = base64.b64encode(buffered.getvalue()).decode("UTF-8")
    return {"body": {"x": img_str}}