create

# File actionpack/lib/action_dispatch/request/session.rb, line 13
      def self.create(store, env, default_options)
        session_was = find env
        session     = Request::Session.new(store, env)
        session.merge! session_was if session_was

        set(env, session)
        Options.set(env, Request::Session::Options.new(store, env, default_options))
        session
      end