refinements.rb

class MyObject
  include SquareMethod
  def method
    "#{square 4}"
  end
end

module SquareMethod
  def square(number)
    number * number
  end
end

#--------------------------

class MyObject
  using SquareMethod
  def method
    "#{4.square}"
  end
end

module SquareMethod
  refine Integer do
    def square(number)
      number * number
    end
  end
end