{
  "foo": "root value"
}
---
Basic:
{{ foo }}
{% set foo = "new value" %}
{{ foo }}
{% with %}
  {% set foo = "new value 2" %}
  {{ foo }}
{% endwith %}
{{ foo }}

Into Loop:
{% for item in [1, 2, 3] %}
  {{ item }}
  {% set item = item * 2 %}
  {{ item }}
{% endfor %}

Conditional:
{% if true %}{% set foo = "was true" %}{% endif %}
{{ foo }}

Multiline:
{% set multiline = "
hello
world" %}
{{ multiline }}

Multiline:
{% set multiline = "hello
world" %}
{{ multiline }}

Block:
{% set var %}This is a {{ foo }}{% endset %}
[{{ var }}]

Filter block
{% set upper_var | upper %}This is a {{ foo }}{% endset %}
[{{ upper_var }}]

Set with +
{% set set_plus = "hello" + "world" %}
{{ set_plus }}