Ada-详细描述在哪里?

我在看 this example ADA中的异常处理。

我需要什么 with 对于 Verbosity_Desired ?

   with Ada.Text_IO;
   with Ada.Exceptions;
   with File_System; use File_System;
   use Ada;
   procedure Main is
   begin
       ... -- call operations in File_System
   exception
       when End_Of_File =>
           Close(Some_File);
       when Not_Found_Error : File_Not_Found =>
           Text_IO.Put_Line(Exceptions.Exception_Message(Not_Found_Error));
       when The_Error : others =>
           Text_IO.Put_Line("Unknown error:");
           if Verbosity_Desired then
               Text_IO.Put_Line(Exceptions.Exception_Information(The_Error));
           else
               Text_IO.Put_Line(Exceptions.Exception_Name(The_Error));
               Text_IO.Put_Line(Exceptions.Exception_Message(The_Error));
           end if;
           raise;
   end Main;