FTS - Custom highlighter in node sdk

Hi all,
i read in this document page this possible paramenter:

This object indicates whether highlighting was requested. The highlight object contains two fields:
style - Optional field that specifies the name of the highlighter, which can be “html”, “ansi”, or a custom highlighter.
fields - Specifies an array of field names to which highlighting is restricted.

but i don’t find a example custom highlighter.
Can you get a exampe for test in PostMan for example?
it would be great even for node sdk :sweat_smile: