'Receive an object instance before that instance is appended
to a result list.
If this method returns EXT_CONTINUE, result appending will proceed
normally.  if this method returns any other value or None,
result appending will not proceed for this instance, giving
this extension an opportunity to do the appending itself, if
desired.
mapper
The mapper doing the operation.
selectcontext
The QueryContext generated from the Query.
row
The result row from the database.
instance
The object instance to be appended to the result.
result
List to which results are being appended.
\**flags
extra information about the row, same as criterion in
``create_row_processor()`` method of
:class:`~sqlalchemy.orm.interfaces.MapperProperty`'

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

    return EXT_CONTINUE
