Inheritance & Instance Variables with Ruby

mammals.rb

class Mammal
  def initialize
    @fur = true
    @milk = true
    @eggs = false
  end

  def generate_lifespan
    @lifespan = rand(7..92)

    self
  end
end

class Dog < Mammal
  def initialize
    @legs = 4

    super
  end
end

# How many instance variables? Which ones?
p Dog.new

# How many instance variables? Which ones?
p Dog.new.generate_lifespan