hook!

# File activesupport/lib/active_support/fork_tracker.rb, line 56
      def hook!
        if Process.respond_to?(:_fork) # Ruby 3.1+
          ::Process.singleton_class.prepend(ModernCoreExt)
        elsif Process.respond_to?(:fork)
          ::Object.prepend(CoreExtPrivate) if RUBY_VERSION < "3.0"
          ::Kernel.prepend(CoreExtPrivate)
          ::Kernel.singleton_class.prepend(CoreExt)
          ::Process.singleton_class.prepend(CoreExt)
        end
      end