9;&#39;&#39;additional validation function, called by validate() of </span>
<span class="sd">           superclass. Here we assume all required self.params are included.</span>
<span class="sd">           If an parameter is found to be invalid, self.valid should be set</span>
<span class="sd">           to False</span>
<span class="sd">        &#39;&#39;&#39;</span>
        <span class="c1"># The url must begin with http</span>
        <span class="k">if</span> <span class="ow">not</span> <span class="bp">s