which (trivially) uses module (ttn-do mogrify) for input:
<http://www.glug.org/software/ttn-do/ttn-do.html.gz#mogrify>

If you grep ttn-do, you'll see other examples, most of which do more
inside ‘editing-buffer’ than outside.  In various versions of Guile,
there is module ‘(ice-9 gap-buffer)’, which is "related technology".

   [...] problem with modules. How to check what can be imported?

You can ‘(set! %load-verbosely #t)’ to check.  On a deeper level, Guile
resolves a module name to a filename using var ‘%load-path’, which is
initialized from env var ‘GUILE_LOAD_PATH’ and command-line arg ‘-L DIR’
(one or more).  By default, cwd is excluded from these, for security.
Try to specify it explicitly, e.g.: "guile -L . -s import-test.scm".

At least, this is my understanding of Guile 1.x -- maybe 2.0 differs.

[clickety click]

Hmm, i see you've successfully tempted me into passing a half hour
playing w/ this stuff.  Well done!  Might as well share the fruit.