how to loop "-boot" action for reboot stress test?

[irreallich]

Sorry, I'm not sure it's appropriate to ask a question here, I am new to lava, I hope to know how to use loop in lava test.

Because our system needs to save some content when rebooting, I hope to test this function, such as rebooting 5000 times, but I don’t know how to add a loop to lava device (jinja2) or job (yaml).
I find the file https://github.com/Linaro/lava-test-plans/blob/master/lava_test_plans/testcases/android-boottime.yaml, It looks like the "-boot" action can be controlled through a for loop.

{% for index in range(1,8)  %}
{% with FASTBOOT_COMMANDS=Null %}
- boot:
{% include "include/boot_target/boot_target.jinja2" %}
{% endwith %}
{% with test_timeout=boottime_timeout %}
{% include "include/test_target.jinja2" %}
{% endwith %}

But when I try the following code,

{% for index in range(1,8)  %}
- boot:
    method: minimal
    timeout:
      minutes: 10
    auto_login:
      login_prompt: 'tegra-ubuntu login:'
      username: root
      password_prompt: "Password:"
      password: "root"
      login_commands:
        - ifconfig
    prompts: 
      - 'root@tegra-ubuntu:'
    parameters:
      kernel-start-message: '' 
    transfer_overlay:
      download_command: cd /tmp ; wget
      unpack_command: tar -m -C / -xzf 
{% endfor %}

lava report error: line22 is "{% for index in range(1,8) %}"

Invalid definition: Loading job submission failed: while scanning for the next token found character that cannot start any token in "", line 22, column 2.

where did I go wrong?