method_resolution.rb

module A
  def foo
    :a
  end
end

module B
  def foo
    :b
  end
end

module D
  def foo
    :d
  end
end

module F
  def foo
    :f
  end
end

module H
  def foo
    :h
  end
end

class C
  include A
  prepend B
  def foo
    :c
  end
end

c = C.new

def c.foo
  :e
end

c.extend D
c.singleton_class.include F
c.singleton_class.prepend H

c.foo