I can never remember the scoping rules for Ruby, so here's an example to remind me.

gistfile1.rb

module A
  module X
    def x
      "X::x"
    end
  end
end

# Won't search in A for X, so need to scope it.
class A::B
  include X rescue nil # :(
  include A::X

  def b
    x
  end
end

puts A::B.new.x


module U
  module Y
    def y
      "Y::y"
    end
  end
end

# Will search for Y in U
module U
  class V
    include Y
    
    def v
      y
    end
  end
end

puts U::V.new.y