Cache

[Revisto]

There is no need to download a song that has been downloaded in the last week.
Each music file we sent has a unique file id (in Telegram) and we can store them and when a music file which we have the file id of that is requested, there is no need to redownload it. This feature makes the bot much faster. But there should be a time period too, like 2 weeks or a month and if the file id we stored was for 6 months ago, it's nice to check it on youtube because maybe there is a new version or change or correct version in youtube.