sberbank.py renamed to app.py
sms.py added
sms.py renamed to models.py
added data models to models.py
added tests.py
CardNumber class added to models.py
added tests for CardNumber
added tests for Visa
added docstring for CardNumber
changed Visa.__init__ parameters
pep8
added Terminal class to models.py
added tests for Terminal
rethinking models
rewriting tests