matedcount_-int"><div class="p">
    <p>A value less than or equal to the number of elements in the sequence,
calculated nondestructively.</p>

<p>The default implementation returns 0. If you provide your own
implementation, make sure to compute the value nondestructively.</p>

<p><strong>Complexity:</strong> O(1), except if the sequence also conforms to <code>Collection</code>.
  In this case, see the documentation of <code>Collection.underestimatedCount</code>.</p>

    <h4>Declaration</h4>    
    <code 