num den
(new-line->lily-string))
(format #f
- "\\time #'~a ~a/~a~a"
+ ;; This is silly but the latter will also work for #f
+ ;; and other
+ (if (key-list? structure)
+ "\\time ~{~a~^,~} ~a/~a~a"
+ "\\time #'~a ~a/~a~a")
structure num den
(new-line->lily-string)))))