module First
  first = 1

  def greet
    p 'hello'
  end
end

module Second
  second = 2

  def self.smile
    p 'smile'
  end
end

class People
  # include First
  extend First
  extend Second

  def eat
    p 'eat'
  end
end

p = People.new
p.greet
# p.smile
People.smile