code: def __init__(
      self,
      path: str,
      dbname: str,
      block_size=_DEFAULT_BLOCK_SIZE,
      serializer: Optional[Serializer] = None,
  ) -> None:
      self._block_size = block_size
      self._path = path
      self._dbname = dbname
      if serializer is None:
          serializer = PickleSerializer()
      self.serializer = serializer
  
      if not os.path.exists(self._path):
          os.makedirs(self._path)
  
      meta_path = os.path.join(self._path, "meta.bin")
  
      info: List[FileInfo] = []
      if os.path.exists(meta_path):
          info = _read_info_list(meta_path)
  
      for v in info:
          if v.file_name == dbname:
              raise ValueError("Dataset name exists")
  
      self._db_path = os.path.join(self._path, self._dbname)
      if os.path.exists(self._db_path):
          raise ValueError("File exists `%s`" % self._db_path)
  
imports: import io
  import os
  import struct
  from typing import List, Optional, Set
  import torch
  import bisect
  import bmtrain
  import json
  from .serializer import Serializer, PickleSerializer
  import random
  import string
  import time
label_desc: Use image node_id 1 to create a new DatasetBuilder object  with example: obj = DatasetBuilder(path, dbname, block_size, serializer)