'Receive an instance before that instance has
its attributes populated.
This usually corresponds to a newly loaded instance but may
also correspond to an already-loaded instance which has
unloaded attributes to be populated.  The method may be called
many times for a single instance, as multiple result rows are
used to populate eagerly loaded collections.
If this method returns EXT_CONTINUE, instance population will
proceed normally.  If any other value or None is returned,
instance population will not proceed, giving this extension an
opportunity to populate the instance itself, if desired.
.. deprecated:: 0.5
Most usages of this hook are obsolete.  For a
generic "object has been newly created from a row" hook, use
``reconstruct_instance()``, or the ``@orm.reconstructor``
decorator.'

def populate_instance(self, mapper, selectcontext, row, instance, **flags):

    return EXT_CONTINUE
