'Receive an object instance before that instance is inserted
into its table.
This is a good place to set up primary key values and such
that aren\'t handled otherwise.
Column-based attributes can be modified within this method
which will result in the new value being inserted.  However
*no* changes to the overall flush plan can be made, and
manipulation of the ``Session`` will not have the desired effect.
To manipulate the ``Session`` within an extension, use
``SessionExtension``.
The return value is only significant within the ``MapperExtension``
chain; the parent mapper\'s behavior isn\'t modified by this method.'

def before_insert(self, mapper, connection, instance):

    return EXT_CONTINUE
