class_docstr: A block-to-block MapTransformFn.
class_docstr_tok: ["A","block-to-block","MapTransformFn","."]
code: def __call__(
      self, input: Iterable[Block], ctx: TaskContext
  ) -> Iterable[Block]:
      yield from self._block_fn(input, ctx)
  
imports: import itertools
  from abc import abstractmethod
  from enum import Enum
  from typing import Any, Callable, Dict, Iterable, List, Optional, TypeVar, Union
  from ray.data._internal.block_batching.block_batching import batch_blocks
  from ray.data._internal.execution.interfaces.task_context import TaskContext
  from ray.data._internal.output_buffer import BlockOutputBuffer
  from ray.data.block import Block, BlockAccessor, DataBatch
label_desc: Use image node_id 2 for calling the BlockMapTransformFn obj's underlying member method code with example usage: obj.__call__(input, ctx) without return types