SICP Exercise 3.1 make-accumulator

Exercise 3.1.  An accumulator is a procedure that is called repeatedly with a single numeric argument and accumulates its arguments into a sum. Each time it is called, it returns the currently accumulated sum. Write a procedure make-accumulator that generates accumulators, each maintaining an independent sum. The input to make-accumulator should specify the initial value of the sum; for example

(define A (make-accumulator 5))
(A 10)
15
(A 10)
25

 SOLUTION

 The code is here:

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