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void?
void

4.18 Void

The constant #<void> is returned by most forms and procedures that have a side-effect and no useful result.

The #<void> value is always eq? to itself.

procedure

(void? v)  boolean?

  v : any/c
Returns #t if v is the constant #<void>, #f otherwise.

procedure

(void v ...)  void?

  v : any/c
Returns the constant #<void>. Each v argument is ignored.