code: def get_zero_hit_rate_search_keys(self) -> Optional[List[str]]:
      if self.provider_metadata_v2 is None:
          return None
  
      zero_hit_search_keys = set()
      for meta in self.provider_metadata_v2:
          if meta.zero_hit_rate_search_keys is not None:
              zero_hit_search_keys.update(
                  meta.zero_hit_rate_search_keys
              )
  
      return list(zero_hit_search_keys)
  
imports: import tempfile
  import time
  from functools import lru_cache
  from typing import Dict, List, Optional
  import pandas
  from upgini import dataset
  from upgini.http import LoggerFactory, ProviderTaskSummary, SearchProgress, SearchTaskSummary, get_rest_client, is_demo_api_key
  from upgini.metadata import SYSTEM_RECORD_ID, FeaturesMetadataV2, FileMetadata, GeneratedFeatureMetadata, ModelTaskType, ProviderTaskMetadataV2, RuntimeParameters
  from upgini.resource_bundle import bundle
  from upgini.spinner import Spinner
label_desc: Use image node_id 5 for calling the SearchTask obj's underlying member method code with example usage: obj.get_zero_hit_rate_search_keys() and returns: list, None