Concern class with model dependent variations

                  module ConfigurableConcern
  extend ActiveSupport::Concern
  VARIATIONS = %I[variation_a variation_b].freeze

  included do
    class_attribute :__configurable_concern_variation, instance_writer: false
  end

  def self.included(base)
    base.__configurable_concern_variation = @__configurable_concern_variation
  end

  VARIATIONS.each do |variation|
    define_singleton_method variation do
      with_variation(variation)
    end

    define_method "#{variation}?" do
      __configurable_concern_variation == variation
    end
  end

  def self.with_variation(variation)
    raise ArgumentError, "Not allowed variation value" if VARIATIONS.exclude?(variation)

    @__configurable_concern_variation = variation
    self
  end

  def example_method
    variation_a? ? 2 : 3
  end
end