title: Add column to query, return inside mapped class in SQLAlchemy
body: <p>It's pretty simple. This works as intented:</p>
  
  <pre><code>&gt;&gt;&gt; db.session.query(SomeModel).all()[0]
  SomeModel(41330029-f21e-4022-aed5-e45e61ada399
  </code></pre>
  
  <p>But if I try to add another column, I get a tuple back:</p>
  
  <pre><code>&gt;&gt;&gt; db.session.query(SomeModel, some_expression.label('foo')).all()[0]
  (SomeModel(41330029-f21e-4022-aed5-e45e61ada399), None)
  </code></pre>
  
  <p>How do I get a flat result? That is, a <code>SomeModel</code> with a <code>foo</code> attribute inside, instead of as a sibling?</p>