[racket] how to design programs chap5 error!!!

How did you produce this error message? 

When I run this program: 

  (require htdp/master)
  (define (check-color x y z w)   x)
  (master check-color)

I get no error whatsoever.  I also don't get an error when I run 

 > (master check-color)

in the interactions area: 

Welcome to DrRacket, version 5.0.99.3--2010-11-29(f11e53c/g) [3m].
Language: Beginning Student.
> (master check-color)
true
>

-- Matthias
 


On Nov 28, 2010, at 6:58 AM, 邢泉 wrote:

>  
> Hi:
>  
> Help Me! Thanks! 
>  
> > (master check-color)
> check-color: this is a procedure, so it must be applied to arguments (which requires using a parenthesis before the name)
>  
>  
> 2010-11-28
> Q.Xing
> _________________________________________________
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>  http://lists.racket-lang.org/listinfo/users

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