DO ncf check_dgii returning None.

[ctactuk]

import stdnum.do.ncf as ncf

ncf.check_dgii(ncf_number, rnc_number)

the method check_dgii always returning None.

[arthurdejong]

The tests still work:

>>> import stdnum.do.ncf as ncf
>>> ncf.check_dgii('130546312', 'A010010011500000038')
{'validation_message': 'El NCF digitado es válido.', 'rnc': '130546312', 'name': 'PROMO NATIONAL SRL', 'type': 'COMPROBANTE GUBERNAMENTAL', 'ncf': 'A010010011500000038', 'status': 'VENCIDO', 'valid_until': '30/04/2018'}