I've just done some stuff with this file to ensure it compiles OK when
running using Guile V1.9.
It declares all it stuff in a module (define-module (scm dislplay-lily)
It currently gets loaded by lily.scm as part of the dynamic load list
near the end of the file. However, things declared as modules for use
in the base 'lily' module are pulled in via a (use-modules) statement
near the start of the file.
Should display-lily.scm move from the ly:load list to the (use-modules)