+# This is technically a has-many; Generation.main_region_id -> Region.id
+Region.generation = relation(Generation, uselist=False)
+Region.version_group_regions = relation(VersionGroupRegion, backref='region',
+ order_by='VersionGroupRegion.version_group_id')
+Region.version_groups = association_proxy('version_group_regions', 'version_group')
+