code: def __init__(
      self,
      chunk_manager: ChunkManager,
      mem_stats_collector: Optional[ChunkMemStatsCollector] = None,
      **kwargs,
  ) -> None:
      self.chunk_manager = chunk_manager
      self.mem_stats_collector: Optional[
          ChunkMemStatsCollector
      ] = mem_stats_collector
  
imports: import functools
  import warnings
  from abc import ABC, abstractmethod
  from time import time
  from typing import Dict, List, Optional, Tuple, Type
  import torch
  from colossalai.utils import get_current_device
  from colossalai.utils.memory import colo_device_memory_capacity
  from colossalai.zero.gemini.chunk import Chunk
  from .chunk import Chunk, ChunkManager
  from .memory_tracer import ChunkMemStatsCollector
label_desc: Use image node_id 1 to create a new PlacementPolicy object from inherited base classes: ABC with example: obj = PlacementPolicy(chunk_manager, mem_stats_collector)