I have been looking at different mods to understand how things work but it seems like adding a new sex trait effect is not obvious (no easy copy-paste from another mod).
Sure, I can add a sex trait with
var sex_traits = {
      killjoy_aura= {
          code = "killjoy_aura",
          name = "",
          descript = "",
          starting = true,
          random_generation = false,
          negative = false,
          acquire_reqs = [],
          reqs = [],
          effects = [{effect = 'killjoy_aura', trigger = 'end_turn'}],
      },
}
func load_tables():      
    modding_core.load_table(Traitdata.sex_traits, sex_traits) 
But then defining the killjoy_aura effect and inserting it to InteractionMainModule.gd seems to be a challenge. If I do it manually without mods it work, 
func killjoy_aura(caster):
     for i in participants:
         i.horny-= 10
         i.sens -= 10
but how to add it by mods? I try to look at what was done in the kennel mod but no idea how to make it work in my case.
I tried
extends "res://gui_modules/Interaction/Scripts/InteractionMainModule.gd"
func killjoy_aura(caster):
     for i in participants:
         i.horny-= 10
         i.sens -= 10
in a extra_effect.gd file and adding
func extend_nodes():
     var sexInteractionNode = modding_core.get_spec_node(input_handler.NODE_SEX)
     modding_core.extend_node(sexInteractionNode, path + '/extra_effect.gd')
but it does not seem to work.
EDIT: Weird Typo
EDIT: Found my problem. Needs to add
[NodeScripts] module_name=true
in mod_config.ini file