indices-a51a528f35c02157e603a20c8796a684">var indices</a> <span class="required">Required</span><div class="comment collapse in" id="comment-indices-a51a528f35c02157e603a20c8796a684"><p>The indices that are valid for subscripting the collection, in ascending
order.</p>
<p>A collection's <code>indices</code> property can hold a strong reference to the
collection itself, causing the collection to be nonuniquely referenced.
If you mutate the collection while iterating over its indices, a strong
reference can r