Class level privates

hello.rb

class Hello
  def self.first
    "Boo!"
  end

  private
  def self.second
    "Buh!"
  end

  class << self
    
    def fourth
      third
    end
    
    private 
    
    def third
      "Bugger"
    end
  end
end

Hello.first # => "Boo!"
Hello.second # => "Buh!"
Hello.third # ~> -:27: private method `third' called for Hello:Class (NoMethodError)
Hello.fourth # => "Bugger"