code: def _get_cache_path(source_file):
      
      local_name = os.path.basename(source_file)
      cache_name = local_name + ".db"
      cache_dir = os.path.join(current_app.instance_path, "classifier")
  
      if not os.path.isdir(cache_dir):
          os.makedirs(cache_dir)
  
      return os.path.abspath(os.path.join(cache_dir, cache_name))
docs: Return the path where the cache should be written/located.
  
      :param onto_name: name of the ontology or the full path
      :return: string, abs path to the cache file