code: def __init__(self, root, transform=None, target_transform=None):
      import lmdb
  
      self.root = os.path.expanduser(root)
      self.transform = transform
      self.target_transform = target_transform
  
      self.env = lmdb.open(
          root,
          max_readers=1,
          readonly=True,
          lock=False,
          readahead=False,
          meminit=False,
      )
      with self.env.begin(write=False) as txn:
          self.length = txn.stat()["entries"]
      cache_file = "_cache_" + root.replace("/", "_")
      if os.path.isfile(cache_file):
          self.keys = pickle.load(open(cache_file, "rb"))
      else:
          with self.env.begin(write=False) as txn:
              self.keys = [key for key, _ in txn.cursor()]
          pickle.dump(self.keys, open(cache_file, "wb"))
  
imports: from __future__ import absolute_import
  from __future__ import division
  import os
  import numpy
  import mxnet
  from mxnet import gluon
  from PIL import Image
  import sys
label_desc: Use image node_id 1 to create a new LSUNClass object from inherited base classes: gluon.data with example: obj = LSUNClass(root, transform, target_transform)