Example #2 - Don't obsess over code DRYness

example2.rb

# Example 2
class Car
  include Checkups

  def maintenance_10k 
    basic_maintenance
  end

  def maintenance_30k
    basic_maintenance
    check_spare_wheel
  end

  def maintenance_50k
    basic_maintenance
    check_spare_wheel
    check_gearbox
  end

  private

  def basic_maintenance
    check_break_fluid
    check_battery_terminals
    check_engine_oil
  end
end