Method SimpleFormula.get_output_period() has no default implementation anymore.
Method SimpleFormula.get_output_period() has no default implementation anymore.

openfisca/openfisca-core,openfisca/openfisca-core,benjello/openfisca-core,sgmap/openfisca-core,adrienpacifico/openfisca-core,benjello/openfisca-core