• Apply your knowledge of Ruby to solve a real world problem.
• Get really good at Ruby classes and objects

Create a program that models a subway system.

The program takes the line and stop that a user is getting on at and the line and stop that user is getting off at and prints the journey and the total number of stops for the trip in the console:

There are 3 subway lines:

Red line

• South Station
• Park Street
• Kendall
• Central
• Harvard
• Porter
• Davis
• Alewife

Green line

• Government Center
• Park Street
• Boylston
• Arlington
• Copley
• Hynes
• Kenmore

Orange line

• North Station
• Haymarket
• Park Street
• State
• Downtown Crossing
• Chinatown
• Back Bay
• Forest Hills

All 3 subway lines intersect at Park Street, but there are no other intersection points.

Tell the user the number of stops between stations using ruby classes.

class Subway
  def stops_between_stations(start_line, start_station, end_line, end_station)
  end
end
  
# One line, all the stations on that line
class Line
end

# One station
class Station
end

And we should be able to find the number of stops with

mbta = Subway.new
mbta.stops_between_stations('Red', 'Alewife', 'Red', 'Alewife') # 0
mbta.stops_between_stations('Red', 'Alewife', 'Red', 'South Station') # 7
mbta.stops_between_stations('Red', 'South Station', 'Green', 'Kenmore') # 6

Tell the user the number of stops between stations AND the stops IN ORDER that they will pass through or change at.

mbta = Subway.new
mbta.stops_between_stations('Red', 'South Station', 'Green', 'Kenmore') 
# "You must travel through the following stops on the Red line:"
# "South Station and Park Street"
# "Change at Park Street."
# "Your trip continues through the following stops on Green Line:" 
# "Boylston, Arlington, Copley, Hines, and Kenmore."
# "7 stops in total."

Use get to allow the user to input their start line, start station, end line, and end station.