def remove_unnecessary_cache_files!
      current_keys = cache_files.map do |file|
        get_cache_key_from_filename(file)
      end
      inmemory_keys = responses.keys

      unneeded_keys = current_keys - inmemory_keys
      unneeded_keys.each do |key|
        File.unlink(filepath_for(key))
      end
    end
def remove_unnecessary_cache_files!
      current_keys = cache_files.map do |file|
        get_cache_key_from_filename(file)
      end
      inmemory_keys = responses.keys

      unneeded_keys = current_keys - inmemory_keys
      unneeded_keys.each do |key|
        File.unlink(filepath_for(key))
      end
    end
Removes any cache files that aren't needed anymore