     }
 }
 
-let DAY: TimeInterval = 60*60*24
 let DAYS_IN_WEEK: Int = 7
-let WEEK: TimeInterval = DAY*TimeInterval(DAYS_IN_WEEK)
 
 extension Date {
     

    //MARK: - Day(s) before/after
    
    func daysBefore(_ days: Int) -> Date? {
        guard let startOfDay = self.startOfDay() else { return nil }
        return startOfDay.addingTimeInterval(-DAY*TimeInterval(days))
    }
    
    func dayBefore() -> Date? {

    //MARK: - Day of Week, Week Number
    
    func dayOfWeek() -> Int? {
        let comp: DateComponents = Calendar.current.dateComponents([.weekday], from: self)
        
        return comp.weekday
    }
    
    func weekNumber() -> Int? {
        let cal: Calendar = Calendar(identifier: Calendar.Identifier.iso8601)
        let comp: DateComponents = cal.dateComponents([.weekOfYear], from: self)
        
        return comp.weekOfYear
    }
