n><span class="anchor" id="line-189"></span><span class="anchor" id="line-190"></span><span class="anchor" id="line-191"></span><span class="anchor" id="line-192"></span><pre> 1. &lt;&lt;Example()&gt;&gt;            - passes None, None
 2. &lt;&lt;Example(a,b)&gt;&gt;         - passes u'a', u'b'
 3. &lt;&lt;Example(,)&gt;&gt;           - passes None, None
 4. &lt;&lt;Example("",)&gt;&gt;         - passes u'', None</pre><span class="anchor" id="line-193"></span><span class="anchor" id="line-194"></span><p cl