gistfile1.txt

{% set row_blocks = [] %}
{% for item in items %}
    {%- if row_width + item.width > 12 %}
        {%- include "rowofstuff.html" %}
        {%- for rowitem in row_blocks %}
            {%- set something = row_blocks.remove(rowitem) %}
        {%- endfor %}
        {%- set row_width = 0 %}
    {%- endif %}
    {%- set something = row_blocks.append(item) %}
    {%- set row_width = row_width + item.width %}
{% endfor %}
{% if row_blocks %}
    {%- include "rowofstuff.html" %}
{% endif %}