 set.</span>
<span class="sd">            x (float):</span>
<span class="sd">                The new x-coordinate of the vertex.</span>
<span class="sd">            y (float): </span>
<span class="sd">                The new y-coordinate of the vertex.</span>

<span class="sd">        Raises:</span>
<span class="sd">            ValueError: If the vertex does not exist in the graph.</span>

<span class="sd">        &quot;&quot;&quot;</span>
        <span class="k">if</span> <span class="n">vertex</span> <spa