main.yml

custom_filter.py

def custom_filter(things):
  equal = set()

  for thing in things:
    ...

  return ...


class FilterModule(object):
    def filters(self):
      return {'custom_filter': custom_filter}

main.yml

---
- name: "Custom filter query"
  set_fact:
    results: "{{ api_response.json | custom_filter }}"
...