# File lib/facebook_web_session.rb, line 92
    def activate_with_previous_session(key, uid=nil, expires=nil)
      # set the expiration
      @session_expires = expires
      
      # set the session key
      @session_key = key
    
      # determine the current user's id
      if uid
        @session_user_id = uid
      else
        result = remote_call("users.getLoggedInUser")
        @session_user_id = result.at("users_getLoggedInUser_response").inner_html
      end
    end