The first argument of most, if not all user defined function is a converter
object. This object gives access to methods to get information on the
conversion context and to methods useful for the conversion, both as an HTML
converter and as a generic Texinfo::Convert::Converter
(see (texi2any_internals)Texinfo::Convert::Converter Helper methods). The
converter can also be used for error reporting as it is also a
Texinfo::Report object (see (texi2any_internals)Texinfo::Report),
and for in-document strings translation as it is also a
Texinfo::Translations object (see (texi2any_internals)Texinfo::Translations). See Error Reporting in User Defined Functions on
error reporting.