Fix doctests by calling self.num_examples after super().__init
Fix doctests by calling self.num_examples after super().__init

udibr/fuel,janchorowski/fuel,dribnet/fuel,dribnet/fuel,mila-udem/fuel,vdumoulin/fuel,mila-udem/fuel,vdumoulin/fuel,aalmah/fuel,dmitriy-serdyuk/fuel,aalmah/fuel,janchorowski/fuel,capybaralet/fuel,udibr/fuel,dmitriy-serdyuk/fuel,capybaralet/fuel