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(define (iota count . maybe-start+step)
;  (check-arg integer? count iota)
  (##sys#check-number count 'iota)
  (if (< count 0) (##sys#error 'iota "Negative step count" iota count))
  (let-optionals maybe-start+step ((start 0) ; Olin, I'm tired of fixing your stupid bugs - why didn't
                                   (step 1) ) ; you use your own macros, then?
    (##sys#check-number start 'iota)
    (##sys#check-number step 'iota)
;    (check-arg number? start iota)
;    (check-arg number? step iota)
    (if (= 0 count)
        '()
        (let loop ((count   count)
                   (val     (+ start (* (- count 1) step)))
                   (ans     '()))
          (if (= 1 count)
              (cons start ans)
              (loop (- count 1) (- val step) (cons val ans)))))))