Like:

`models.py`
```python
...

@property
is_indexable(self):
return (doc.is_template or doc.is_archived or
        doc.category in (ADMINISTRATION_CATEGORY,
                         CANNED_RESPONSES_CATEGORY))

...
```

`document.html`
```jinja2
...

{% if document.is_indexable %}
  {% set meta = meta + [('robots', 'noindex')] %}
{% endif %}

...
```