code: def __del__(self):
      if self.block_tables is not None and self.block_tables:
          # Free blocks
          get_cache_manager().free(
              list(itertools.chain.from_iterable(self.block_tables))
          )
  
imports: import math
  import time
  import itertools
  import torch
  import torch.distributed
  import numpy
  from dataclasses import dataclass
  from opentelemetry import trace
  from transformers import PreTrainedTokenizerBase
  from typing import Optional, Tuple, List, Type, Dict
  from text_generation_server.models import Model
  from text_generation_server.utils.tokens import batch_top_tokens
  from text_generation_server.utils.speculate import get_speculate
  from text_generation_server.models.types import Batch, Tokens, Generation, GeneratedText
  from text_generation_server.models.cache_manager import get_cache_manager, set_cache_manager, BLOCK_SIZE
  from text_generation_server.pb import generate_pb2
  from text_generation_server.utils import StoppingCriteria, HeterogeneousNextTokenChooser
  from text_generation_server.utils.dist import MEMORY_FRACTION
label_desc: Use image node_id 5 for calling the FlashCausalLMBatch obj's underlying member method code with example usage: obj.__del__() without return types