. The internal logic
belongs to the view controller. <code>Context</code> answers the questions <em>What to I need to present a ProductViewController</em> and <em>Am I
already presenting a ProductViewController for this product</em>.</p>

                        <a href="Protocols/Factory.html" class="slightly-smaller">See more</a>
                      </div>
                      <div class="declaration">
                        <h4>Declaration</h4>
                        <div class="language">
         