class="block">Compute the union of two regions.</div>
<dl><dt><span class="strong">Parameters:</span></dt><dd><code>region1</code> - first region (will be unusable after the operation as
 parts of it will be reused in the new region)</dd><dd><code>region2</code> - second region (will be unusable after the operation as
 parts of it will be reused in the new region)</dd>
<dt><span class="strong">Returns:</span></dt><dd>a new region, result of <code>region1 union region2</code></dd></dl>
</li>
</ul>
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