Adding class methods

Car.rb

class Car 
  attr_accessor :color, :year, :make, :model
  @@all = []
  def initialize(color, year, make, model)
    @color = color
    @year = year 
    @make = make
    @model = model
    @@all << self
  end
  
  def get_vin
    puts self
  end
  
  def years_old
    Time.now.year - self.year
  end
  
  def self.all 
    @@all
  end
end