{{ }} tells the template to print the value, this won't work in expressions like you're trying to do. Instead, use the {% set %} template tag and then assign the value the same way you would in normal python code.

{% set testing = 'it worked' %}
{% set another = testing %}
{{ another }}

Result:

it worked

Nice shorthand for Multiple variable assignments

{% set label_cls, field_cls = "col-md-7", "col-md-3" %}

Just Set it up like this

{% set active_link = recordtype -%}

You can do this with the set tag. See the official documentation.

For example,

{% set foo = "bar" %}
{{ foo }}

outputs

bar

Note: there are scoping issues which means that variable values don’t persist between loop iterations, for example, if you want some output to be conditional on a comparison between previous and current loop values:

{# **DOES NOT WORK AS INTENDED** #}

{% set prev = 0 %}
{% for x in [1, 2, 3, 5] %}
{%- if prev != x - 1 %}⋮ (prev was {{ prev }})
{% endif -%}
{{ x }}
{%- set prev = x %}
{% endfor %}

prints

1
⋮ (prev was 0)
2
⋮ (prev was 0)
3
⋮ (prev was 0)
5

because the variable isn’t persisted. Instead you can use a mutable namespace wrapper:

{% set ns = namespace(prev=0) %}
{% for x in [1, 2, 3, 5] %}
{%- if ns.prev != x - 1 %}⋮ (ns.prev was {{ ns.prev }})
{% endif -%}
{{ x }}
{%- set ns.prev = x %}
{% endfor %}

which prints

1
2
3
⋮ (ns.prev was 3)
5

as intended.