code: def build(self) -> Block:
      if self._builder is None:
          if self._empty_block is not None:
              self._builder = BlockAccessor.for_block(
                  self._empty_block
              ).builder()
              self._builder.add_block(self._empty_block)
          else:
              self._builder = ArrowBlockBuilder()
      return self._builder.build()
  
file_path: ray/python/ray/data/_internal/delegating_block_builder.py
imports: import collections
  from typing import Any, Mapping
  from ray.data._internal.arrow_block import ArrowBlockBuilder
  from ray.data._internal.block_builder import BlockBuilder
  from ray.data._internal.pandas_block import PandasBlockBuilder
  from ray.data.block import Block, BlockAccessor, DataBatch
label_desc: Use image node_id 6 for calling the DelegatingBlockBuilder obj's underlying member method code with example usage: obj.build() and returns: self