title: How to merge a nested object with parent in marshmallow (+ sqlalchemy)?
body: <p>From their example <a href="https://marshmallow.readthedocs.org/en/latest/quickstart.html#nesting-serializers" rel="nofollow">https://marshmallow.readthedocs.org/en/latest/quickstart.html#nesting-serializers</a></p>
  
  <p>How do you get a merged result instead of nested?
  Expected result:</p>
  
  <pre><code>user = User(name="Monty", email="monty@python.org")
  blog = Blog(title="Something Completely Different", author=user)
  serialized = BlogSerializer(blog)
  serialized.data
  # {'created_at': 'Sun, 10 Nov 2013 16:10:57 -0000',
  #  'email': u'monty@python.org',
  #  'name': u'Monty',
  #  'title': u'Something Completely Different'}
  </code></pre>