+
+ # Pretend to prune unused domains and users. Some "what if"
+ # information will be output to stdout.
+ #
+ # The prune mode is the main application of the "dummy" runners,
+ # since it performs some computation outside of the plugins
+ # themselves. This lets the user know which users and domains would
+ # be removed and can help prevent mistakes or even find bugs in the
+ # prune code, if it looks like something will be removed that
+ # shouldn't be!
+ #
+ # @param cfg [Configuration] the configuration options to pass to
+ # the *plugin* we're runnning.
+ #
+ # @param plugin [Class] plugin class that will do the pruning.
+ #
+ def run(cfg, plugin)