// TODO:
// pdf reader copy past, night mode... features
// premiem feature (annual subscribtion) // siler - 100 etb (reader activity will be ad free) // gold - 150 etb - all ads will be removed
// note taking feature
// delete subject file
//send subject units
// reward user when invite others through phone // verify phone with yegara sms
// desktop app (through c# if possible)