ly:version? unbound variable

[Stefano Troncaro]

Hi everyone! According to this page in the manual the function ly:version? should be implemented, but the example given fails with the error 'unbound variable: ly:version?' which suggests it's not. I'm running it in 2.19.83, was this function deleted and the documentation not updated?

Copying the example here:

#(cond
  ((ly:version? > '(2 20))
   (ly:message "This is code to run for LilyPond after 2.20"))
  ((ly:version? = '(2 19 57))
   (ly:message "This will only be executed with LilyPond 2.19.57"))
  (else (ly:message "This will be executed in any other version")))

Does anyone know what is happening?

Thanks you!