code: def __init__(
      self,
      num_blocks_per_task: int,
      block_size: int,
      data_format: str,
      num_columns: int,
  ):
      self.num_blocks_per_task = num_blocks_per_task
      self.block_size = block_size
      self.data_format = data_format
      self.num_columns = num_columns
  
imports: import argparse
  import json
  import time
  from typing import Dict, List, Any
  import pandas
  import pyarrow
  import numpy
  import ray
  from ray.data.block import BlockMetadata
  from ray.data.context import DataContext, DEFAULT_TARGET_MAX_BLOCK_SIZE
  from ray.data.datasource import Datasource, ReadTask, Reader
label_desc: Use image node_id 1 to create a new BlockReader object from inherited base classes: Reader with example: obj = BlockReader(num_blocks_per_task, block_size, data_format, num_columns)