HA - A Trigger-based Template sensor extracting events from multiple calendars and sorting them by start

multical_event.yaml

template:
  - trigger:
      - platform: calendar
        event: start
        entity_id: calendar.a
      - platform: calendar
        event: start
        entity_id: calendar.b
      - platform: calendar
        event: end
        entity_id: calendar.a
      - platform: calendar
        event: end
        entity_id: calendar.b
    action:
      - service: calendar.get_events
        data:
          duration:
            hours: 72
        target:
          entity_id:
            - calendar.a
            - calendar.b
        response_variable: calendars
      - variables:
          e: |
            {% set ns = namespace(cal_events=[]) %}
            {%- for key, value in calendars.items() %}
              {%- for event in value.events %}
                {%- set ns.cal_events = ns.cal_events + [event] %}
              {%- endfor %}
            {%- endfor %}
            {{ ns.cal_events | sort(attribute='start') | list }}
    sensor:
      - name: MultiCal 72 hour agenda
        state: "{{ e | count }}"
        attributes:
          events: "{{e}}"
          entity_id: |
            {{['calendar.a','calendar.b']}}

Can you please take a look because I did something wrong:

- trigger:
  - platform: calendar
    event: start
    entity_id: calendar.prazniki_v_sloveniji
  - platform: calendar
    event: start
    entity_id: calendar.f1
  - platform: calendar
    event: end
    entity_id: calendar.moto_gp
  - platform: calendar
    event: end
    entity_id: calendar.odvoz_odpadkov
  - platform: calendar
    event: end
    entity_id: calendar.dom
  - platform: calendar
    event: end
    entity_id: calendar.robert
  action:
    - service: calendar.get_events
      data:
        duration:
          hours: 72
      target:
        entity_id:
          - calendar.prazniki_v_sloveniji
          - calendar.f1
          - calendar.moto_gp
          - calendar.odvoz_odpadkov
          - calendar.dom
          - calendar.robert
      response_variable: calendars
    - variables:
        e: |
          {% set ns = namespace(cal_events=[]) %}
          {%- for key, value in calendars.items() %}
            {%- for event in value.events %}
              {%- set ns.cal_events = ns.cal_events + [event] %}
            {%- endfor %}
          {%- endfor %}
          {{ ns.cal_events | sort(attribute='start') | list }}
  sensor:
    - name: MultiCal 72 hour agenda
      state: "{{ e | count }}"
      attributes:
        events: "{{e}}"
        entity_id: |
          {{['calendar.prazniki_v_sloveniji','calendar.f1','calendar.moto_gp','calendar.odvoz_odpadkov','calendar.dom','calendar.robert', ]}}