def __init__(self, loader: DataLoader, num_prefetches: int = None):
        """Loader wrapper. Prefetches specified number of batches on the GPU.

        Args:
            loader: torch dataloader.
            num_prefetches: number of batches to prefetch on the GPU.
        """
        super().__init__(loader)
        self.num_prefetches = num_prefetches or 1
Loader wrapper. Prefetches specified number of batches on the GPU.

        Args:
            loader: torch dataloader.
            num_prefetches: number of batches to prefetch on the GPU.
        
catalyst/data/loader.py