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Using the apply Procedure

Use apply when you have the arguments to a procedure bundled up in an argument list (like the list subs in answer-by-pattern).

Suppose argument-list has the form 

          (arg1 arg2 ... argn)
Then 
          (apply procedure argument-list)
has the same effect as 
          (procedure arg1 arg2 ... argn)
Compare 
          (+ 3 5 8) ⇒ 16
and 
          (apply + '(3 5 8)) ⇒ 16
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