void TestR2()
        {
            "Demonstrating Requirement #2".title();
            //creating new element of type int and string
            DBElement <int, string> element = new DBElement <int, string>();

            element.name      = "first element of db";
            element.descr     = "int and string type";
            element.timeStamp = DateTime.Now;
            element.children.AddRange(new List <int> {
                0, 2, 4, 8
            });
            element.payload = "first element's payload";
            element.showElement();
            db.insert(1, element);
            db.showDB();
            WriteLine();
            //creating new element of type string and list of strings
            DBElement <string, List <string> > element2 = new DBElement <string, List <string> >();

            element2.name      = "second element of db";
            element2.descr     = "strings and strings of string types";
            element2.timeStamp = DateTime.Now;
            element2.children.AddRange(new List <string> {
                "SMA", "OOD", "Project2"
            });
            element2.payload = new List <string> {
                "second", "SMA", "project"
            };
            element2.showEnumerableElement();
            db2.insert("2", element2);
            db2.showEnumerableDB();
            WriteLine();
        }
        void TestR7()
        {
            //Demonstrating queries
            "Demonstrating Requirement #7".title();
            WriteLine();
            QueryEngine             queryv      = new QueryEngine();
            DBElement <int, string> displayresc = new DBElement <int, string>();
            DBElement <int, string> displayres  = new DBElement <int, string>();

            //demonstrating query 1
            Console.WriteLine("\n \n getting value for key 1");
            displayres = queryv.queryvalue <int, DBElement <int, string>, string>(db, 1);
            if (displayres != null)
            {
                displayres.showElement();
            }

            DBElement <string, List <string> > valuestring = new DBElement <string, List <string> >();

            Console.WriteLine("\n \n getting value for key 2");
            valuestring = queryv.queryvalue <string, DBElement <string, List <string> >, string>(db2, "2");
            if (valuestring != null)
            {
                valuestring.showEnumerableElement();
            }

            // demonstrating query 2
            Console.WriteLine("\n \n getting children for key 1");
            List <int> tchildlist = new List <int>();

            tchildlist = queryv.querychildren <int, DBElement <int, string>, string>(db, 1);
            if (tchildlist != null)
            {
                foreach (int i in tchildlist)
                {
                    Console.WriteLine(i);
                }
            }
        }
        static void Main(string[] args)
        {
            "Testing DBEngine Package".title('=');;
            WriteLine();

            "Test db of scalar elements".title();
            WriteLine();
            //creation of new elements
            DBElement <int, string> elem1 = new DBElement <int, string>();

            elem1.payload = "a payload";

            DBElement <int, string> elem2 = new DBElement <int, string>("Darth Vader", "Evil Overlord");

            elem2.payload = "The Empire strikes back!";

            var elem3 = new DBElement <int, string>("Luke Skywalker", "Young HotShot");

            elem3.payload = "X-Wing fighter in swamp - Oh oh!";

            if (verbose)
            {
                Write("\n --- Test DBElement<int,string> ---");
                WriteLine();
                elem1.showElement();
                WriteLine();
                elem2.showElement();
                WriteLine();
                elem3.showElement();
                WriteLine();
            }

            Write("\n --- Test DBEngine<int,DBElement<int,string>> ---");
            WriteLine();

            int        key    = 0;
            Func <int> keyGen = () => { ++key; return(key); };  // function to generate keys

            // new database created
            DBEngine <int, DBElement <int, string> > db = new DBEngine <int, DBElement <int, string> >();
            bool p1 = db.insert(keyGen(), elem1);
            bool p2 = db.insert(keyGen(), elem2);
            bool p3 = db.insert(keyGen(), elem3);

            if (p1 && p2 && p3)
            {
                Write("\n  all inserts succeeded");
            }
            else
            {
                Write("\n  at least one insert failed");
            }
            db.showDB();
            WriteLine();

            "Test db of enumerable elements".title();
            WriteLine();
            //new element created
            DBElement <string, List <string> > newelem1 = new DBElement <string, List <string> >();

            newelem1.name    = "newelem1";
            newelem1.descr   = "test new type";
            newelem1.payload = new List <string> {
                "one", "two", "three"
            };
            //new element created
            DBElement <string, List <string> > newerelem1 = new DBElement <string, List <string> >();

            newerelem1.name    = "newerelem1";
            newerelem1.descr   = "better formatting";
            newerelem1.payload = new List <string> {
                "alpha", "beta", "gamma"
            };
            newerelem1.payload.Add("delta");
            newerelem1.payload.Add("epsilon");
            //new element created
            DBElement <string, List <string> > newerelem2 = new DBElement <string, List <string> >();

            newerelem2.name  = "newerelem2";
            newerelem2.descr = "better formatting";
            newerelem2.children.AddRange(new List <string> {
                "first", "second"
            });
            newerelem2.payload = new List <string> {
                "a", "b", "c"
            };
            newerelem2.payload.Add("d");
            newerelem2.payload.Add("e");

            if (verbose)
            {
                Write("\n --- Test DBElement<string,List<string>> ---");
                WriteLine();
                newelem1.showEnumerableElement();
                WriteLine();
                newerelem1.showEnumerableElement();
                WriteLine();
                newerelem2.showEnumerableElement();
                WriteLine();
            }

            Write("\n --- Test DBEngine<string,DBElement<string,List<string>>> ---");

            int           seed    = 0;
            string        skey    = seed.ToString();
            Func <string> skeyGen = () =>
            {
                ++seed;
                skey = "string" + seed.ToString();
                skey = skey.GetHashCode().ToString();
                return(skey);
            };

            DBEngine <string, DBElement <string, List <string> > > newdb =
                new DBEngine <string, DBElement <string, List <string> > >();

            newdb.insert(skeyGen(), newelem1);
            newdb.insert(skeyGen(), newerelem1);
            newdb.insert(skeyGen(), newerelem2);
            newdb.showEnumerableDB();
            Write("\n\n");
        }