Ansible variable substring from regex_replace

substr.yml

---

# RUN: ansible-playbook -i localhost, substr.yml
- hosts: localhost

  vars:
    stuff: deekayen@WINDOMAIN.COM
    ansible_user: deekayen

  tasks:
    - name: "Crop stuff var into substr var."
      set_fact:
        substr: "{{ stuff | regex_replace('^(.*?)@WINDOMAIN.COM$', '\\1') }}"


    - name: "Return deekayen."
      debug:
        var: substr