public override void Register(Person person)
        {
            if (person is TaxiDriver)
            {
                if (!this.people.ContainsValue(person))
                {
                    this.drivers[person.Name] = person;
                }
            }
            else
            {
                if (!this.people.ContainsValue(person))
                {
                    this.people[person.Name] = person;
                }
            }

            person.TaxiStation = this;
        }
 public abstract void Register(Person person);