            <p>… create a bullet just below the invader that will move
downward…</p>

            </div>
            
            <div class="content"><div class='highlight'><pre>        <span class="hljs-keyword">var</span> bullet = <span class="hljs-keyword">new</span> Bullet({ x: <span class="hljs-keyword">this</span>.center.x, y: <span class="hljs-keyword">this</span>.center.y + <span class="hljs-keyword">this</span>.size.y / <span class="hljs-number">2</span> },
                                { x: