Design a city bike sharing system. Write a Bike class with methods to checkout and return a bike. Write a BikeStation class initialized with a settable max capacity, and with methods to add a bike and add a sponsor. Write a BikeShare class with methods to add a bike, to assign a bike to an available station, to list all bikes, and to list checked out bikes. As a bonus, allow new bikes to be randomly assigned to a home station with probabilities 50% for station 1, 20% for station 2, 20% for station 3, and 10% for station 4.
