gistfile1.rb

module IncludeMe;end
module BehindTheScenes;end

# Include IncludeMe in a module
module One
  include IncludeMe
end

# Add an ancestor to IncludeMe
module IncludeMe
  include BehindTheScenes
end

# Include it in another module after adding that ancestor
module Two
  include IncludeMe
end

# prints [One, IncludeMe]
puts "ancestors after reverse-order includes: #{One.ancestors.inspect}"

# prints [Two, IncludeMe, BehindTheScenes]
puts "ancestors after normal includes: #{Two.ancestors.inspect}"