span name="DBIO" class="extype">DBIO</span>. This is to allow
overriding of return types with more specific types. <span name="Query" class="extype">Query</span> is invariant, so it cannot be subclassed, while
<span name="DBIO" class="extype">DBIO</span> is covariant.</p><p>Created by leslie.lam on 2/7/18.</p><p>TODO can we make implicits with this? or modify the generator to have them? very difficult to read.
move all these to the generator? decorate each class with these query methods?</p><p>autogenerate 