code: def GetRowCache(self, query):
      
      query_hash = hash(query)
      if query_hash not in self._row_caches:
        self._row_caches[query_hash] = set()
      return self._row_caches[query_hash]
docs: Retrieves the row cache for a specific query.
  
      The row cache is a set that contains hashes of values in a row. The row
      cache is used to find duplicate row when a database and a database with
      a WAL file is parsed.
  
      Args:
        query (str): query.
  
      Returns:
        set: hashes of the rows that have been parsed.