A multi-valued function, the values consisting of a
<rope-transpose> pointer to the leaf of rope corresponding
to index, and a new index for the position of index inside
the leaf itself.
(define r (cons->rope '(("La " . "vie ") .("est " . "ailleurs"))))
(rope-transpose-from-index r 8)
⇒ #<<rope-transpose> node: "est " ... >
⇒ 1
Example 2.21: Obtaining a <rope-transpose> pointer from a given
index.
Notice that the ninth character of the string ‘La vie est ailleurs’
is the second character of the string ‘est ’. Thus the first value
of rope-transpose-from-index gives us a <rope-transpose>
pointer to the string ‘est ’ and the second value is the local
index in that string.