classmethod.rb

puts 'start'

# docs
class Hoge
  # body
  def mog
    puts 'this is instance method'
  end

  def para
    puts 'this is instance method 2'
  end

  # def self.mog
  #   puts 'this is class method'
  # end

  class << self
    def mog
      puts 'this is another class method'
    end

    def para
      puts 'this is another instance method 2'
    end
  end
end

Hoge.new.mog
Hoge.mog

Hoge.new.para
Hoge.para