Ansible template a variable

test.yml

- hosts: 127.0.0.1
  connection: local
  gather_facts: no
  tasks:
    - set_fact:
        my_templated_var: |
          {
            {% for key in ["foo", "bar"] %}
            "{{ key }}": 1,
            {% endfor %}
            "end": 0
          }

    - debug: var=my_templated_var

    - debug: msg="bar is {{ my_templated_var["bar"] }}"