Ejabberd.Config.OptsFormatter.format_opts_for_ejabberd

You're seeing just the function format_opts_for_ejabberd, go back to Ejabberd.Config.OptsFormatter module for more information.
Link to this function

format_opts_for_ejabberd(opts)

Specs

format_opts_for_ejabberd([{atom(), any()}]) :: list()

Takes a keyword list with keys corresponding to the keys requested by the ejabberd config (ex: modules: mods) and formats them to be correctly evaluated by ejabberd.

Look at how Config.get_ejabberd_opts/0 is constructed for more informations.