How to indent nested if/for statements in jinja2 - nested

Question

I have a long Jinja2 template which has many nested if/for statements. It's very hard to read. I would like to indent the {% %} bits, to make it clearer.
However if I do that, the contents of those blocks gets indented further too.
How can I indent just the {% %} bits?
I'm using Ansible.
Steps to reproduce:
template.yaml.j2
{% for x in range(3) %}
Key{{ x }}:
# The following should be one list
- always here
{% if x % 2 %}
- sometimes here
{% endif %}
{% endfor %}
playbook.yaml
---
- hosts: localhost
connection: local
tasks:
- template:
src: template.j2
dest: template.yaml
Run with ansible-playbook playbook.yaml
Desired Output
Key0:
# The following should be one list
- always here
Key1:
# The following should be one list
- always here
- sometimes here
Key2:
# The following should be one list
- always here
Actual behavior:
Key0:
# The following should be one list
- always here
Key1:
# The following should be one list
- always here
- sometimes here
Key2:
# The following should be one list
- always here
Workaround
If I unindent the if statements like:
{% for x in range(3) %}
Key{{ x }}:
# The following should be one list
- always here
{% if x % 2 %}
- sometimes here
{% endif %}
{% endfor %}
Then I get the output I want.
But the problem is that this is hard to read. (In my actual template, I have if statements inside for inside if, etc. Highly nested.)

Answer 1

Q: "How to indent nested if/for statements in Jinja2?"
A: Turn off default trimming and manually ltrim only indented control statements {%-. For example, the template below does what you're looking for
shell> cat templates/template.j2
#jinja2: trim_blocks: False
{% for x in range(3) %}
Key{{ x }}:
# The following should be one list
- always here
{%- if x % 2 %}
- sometimes here
{%- endif %}
{%- endfor %}
The task
- template:
src: template.j2
dest: template.yaml
creates the file template.yaml
shell> cat template.yaml
Key0:
# The following should be one list
- always here
Key1:
# The following should be one list
- always here
- sometimes here
Key2:
# The following should be one list
- always here
See Whitespace Control.
Notes
The dash in {%- endfor %} removes the empty line among the keys.
By default parameter trim_blocks: yes. See template.
The documentation section Whitespace Control says:
You can manually disable the trim_blocks behavior by putting a plus sign (+) at the end of a block
Then, the following template gives the same result
shell> cat templates/template.j2
{% for x in range(3) %}
Key{{ x }}:
# The following should be one list
- always here
{%- if x % 2 +%}
- sometimes here
{%- endif +%}
{% endfor %}