How the match works
For each item in the collection, Bindary reads the property named here and looks for a child element whose
b-item-id equals that value. That element renders the item; the others are skipped.
<li b-repeat="items" b-repeat-item-id="category">
<span b-item-id="warm"></span> <!-- renders items where category is "warm" -->
<span b-item-id="metal"></span> <!-- renders items where category is "metal" -->
</li>
An item whose property matches no template renders nothing, which is a quiet way to filter but not what
filter is for.