Roman numerals in my number sequence

[Adam Good]

Hello,
Considering that fretboard diagrams can use (number-type .
roman-lower) how can I get scheme to print Roman numerals in place of
Arabic numbers in the following sequence?

Thanks!!!!
Adam

@@@
\version "2.12.3"

#(define sequence-number 0)

#(define-markup-command (score-sequence layout props sequence-number)
  (number?)
  (interpret-markup layout props
    (markup #:circle (number->string sequence-number))))

#(set! sequence-number (1+ sequence-number))
\markup { \score-sequence #sequence-number }

#(set! sequence-number (1+ sequence-number))
\markup { \score-sequence #sequence-number }

#(set! sequence-number (1+ sequence-number))
\markup { \score-sequence #sequence-number }