             }
             else {
                 return iter(a + 1)
-//                return false
             }
         }
         return iter((-1)*bound)

    */
    
    func forall(s: FuncSet, p: FuncSetIndication) -> Bool {
//        var iter: (Int) -> (Bool) = { _ in false }
//        iter = {
//            a in

    func toString(s: FuncSet) -> String {
        
        let array = Array(-self.bound ... self.bound).filter { self.contains(s, elem: $0) }
        let string = array.map { (g) in return "\(g)" }.joinWithSeparator(", ")
        return string
    }
    
