{#
This is somewhat subtle.
Checkboxes have a name and value, and when the checkbox is ticked, the form posts
with name=value. If the checkbox is unticked, the field just isn't present at all.
This is distinct from 'checked', which determines whether the checkbox appears
at all. (So, it's not symmetric to the code above.)
#}
{% if form.terms.errors %}
{% for error in form.terms.errors %}