public string AddBusTicket(string from, string to, string busCompany, DateTime dateTime, decimal price)
        {
            BusTicket ticket = new BusTicket(from, to, busCompany, dateTime, price);
            string key = ticket.UniqueKey;
            string result;

            if (this.ticketCatalog.ContainsKey(key))
            {
                result = "Duplicated " + ticket.Type.ToString().ToLower();
            }
            else
            {
                this.ticketCatalog.Add(key, ticket);
                string fromToKey = ticket.FromToKey;
                this.ticketCatalogByFromToKey.Add(fromToKey, ticket);
                this.ticketCatalogByDateAndTimeKey.Add(ticket.DateAndTime, ticket);
                result = ticket.Type + " created";
            }

            if (result.Contains("created"))
            {
                this.busTicketsCount++;
            }

            return result;
        }
        public string DeleteBusTicket(string from, string to, string busCompany, DateTime dateTime)
        {
            BusTicket ticket = new BusTicket(from, to, busCompany, dateTime);
            string result = this.DeleteTicket(ticket);

            if (result.Contains("deleted"))
            {
                this.busTicketsCount--;
            }

            return result;
        }