SICP Exercise 3.55 partial-sums

Exercise 3.55.  Define a procedure partial-sums that takes as argument a stream S and returns the stream whose elements are S0, S0 + S1, S0 + S1 + S2, .... For example, (partial-sums integers) should be the stream 1, 3, 6, 10, 15, ....

 SOLUTION

 The code and tests are here.

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