Q3: Partial sums

Define a function partial-sums, which takes in a stream with elements

a1, a2, a3, ...

and outputs the stream

a1, a1 + a2, a1 + a2 + a3, ...

If the input is a finite stream of length n, the output should be a finite stream of length n. If the input is an infinite stream, the output should also be an infinite stream.

(define (partial-sums stream) 'YOUR-CODE-HERE (helper 0 stream) )