def write
      @cache["version"] = VERSION
      File.open(CACHE_FILE, "w") do |fh|
        fh.puts(JSON.dump(@cache))
      end
    end
def write
      @cache["version"] = VERSION
      File.open(CACHE_FILE, "w") do |fh|
        fh.puts(JSON.dump(@cache))
      end
    end
Write the cache to disk.

 @return [void]