code: def CheckHash(self, responses):
      
      index = responses.request_data["index"]
  
      if index not in self.state.pending_files:
        # This is a blobhash for a file we already failed to read and logged as
        # below, check here to avoid logging dups.
        return
  
      file_tracker = self.state.pending_files[index]
  
      hash_response = responses.First()
      if not responses.success or not hash_response:
        urn = file_tracker["stat_entry"].pathspec.AFF4Path(self.client_urn)
        self.Log("Failed to read %s: %s", urn, responses.status)
        self._FileFetchFailed(index, responses.request.request.name)
        return
  
      file_tracker.setdefault("hash_list", []).append(hash_response)
  
      self.state.blob_hashes_pending += 1
  
      if self.state.blob_hashes_pending > self.MIN_CALL_TO_FILE_STORE:
        self.FetchFileContent()
docs: Adds the block hash to the file tracker responsible for this vfs URN.