t</span> <span class="nb">isinstance</span><span class="p">(</span><span class="n">velocity</span><span class="p">,</span> <span class="nb">list</span><span class="p">):</span>
            <span class="c1"># List not passed -- set all velocities equal</span>
            <span class="bp">self</span><span class="o">.</span><span class="n">velocity</span> <span class="o">=</span> <span class="p">[</span><span class="n">velocity</span> <span class="k">for</span> <span class="n">i</span> <span class="ow">in</spa