;;; beatStructure gets a list of (3 3 3 ...), where the number of entries is the
;;; number of beats, each containing 3 base-moments, if the time
;;; signature numerator is greater than 3 and divisible by 3, and
;;; a list of (1 1 1 ...), where the number of entries is the
;;; number of base moments in a measure otherwise.
;;; beatStructure gets a list of (3 3 3 ...), where the number of entries is the
;;; number of beats, each containing 3 base-moments, if the time
;;; signature numerator is greater than 3 and divisible by 3, and
;;; a list of (1 1 1 ...), where the number of entries is the
;;; number of base moments in a measure otherwise.