OK, so I have got the latest NuGet package for the tool kit installed in my app.

Now I want to add it to my xaml. So in the toolkit samples for TableOfContents they have (something like):
<SPAN class="token tag"><SPAN class="token tag"><SPAN class="punctuation token"><</SPAN><SPAN class="namespace token">esri:</SPAN>TableOfContents</SPAN> <SPAN class="attr-name token">Grid.Row</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>0<SPAN class="punctuation token">"</SPAN></SPAN> <SPAN class="attr-name token"><SPAN class="namespace token">x:</SPAN>Name</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>toc<SPAN class="punctuation token">"</SPAN></SPAN>
<SPAN class="attr-name token">GeoView</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>{Binding ElementName<SPAN class="punctuation token">=</SPAN>MyMapView}<SPAN class="punctuation token">"</SPAN></SPAN> <SPAN class="attr-name token">ShowLegend</SPAN><SPAN class="attr-value token"><SPAN class="punctuation token">=</SPAN><SPAN class="punctuation token">"</SPAN>false<SPAN class="punctuation token">"</SPAN></SPAN> <SPAN class="punctuation token">/></SPAN></SPAN><SPAN class="line-numbers-rows"><SPAN></SPAN><SPAN></SPAN></SPAN>But the namespace of esri does not have a TableOfContents so what name space do I need to add to my app and reference in my element?
