Homework submission for week 1 day 3 -  Subway

The main challenge that I had was trying to figure out whether i could access variables in one method from another method. I couldn't figure this out so I resorted to passing the variable as an argument down the chain of methods (I only called one method to start this chain reaction).

The code is working, though I have a feeling that it could be much shorter... maybe something ill know how to do in the future.

The other challenge I had was figuring out whether I could access a hash from a method without it having to be in the method. I couldn't figure this out so I just put it in the method itself (i.e. the subway_lines) hash.
Just a nitpick, you won't usually put an extra new line here. Normally if you wanted an extra line you would do that in the "formatting logic" (the `puts`)