This example shows how to "customize" another configuration file, that
is, how to make configuration variations without actually editing or
copy/pasting the common configuration file.

In this example, config_red.fmpp and config_dark.fmpp executes a
slightly modified version of config.fmpp. To try them type:

  fmpp -C config_red.fmpp

and

  fmpp -C config_dark.fmpp

respectively.