dog.py

class Dog(object):
    def __init__(self):
        self.dict_ = {}
        self.__dict__

    def add(self, name, breed):
        self.dict_[name] = breed

    def __repr__(self):
        return 'Dog({}, {})'.format(*self.dict_.items())


class Dog(object):

    def add(self, name, breed):
        self.__dict__['name'] = name
        self.__dict__['breed'] = breed

    def __repr__(self):
        return 'Dog({}, {})'.format(self.__dict__['name'],
                                    self.__dict__['breed']) 


>>> dog = Dog()
>>> dog.add('Fido', 'Mastiff')
>>> dog.name
'Fido'
>>> dog.breed
'Mastiff'

class Dog(object):

    def __init__(self, name, breed):
        self.name = name
        self.breed = breed

    def __repr__(self):
        return 'Dog({}, {})'.format(self.name, self.breed) 

>>> dog = Dog('Fido', 'Mastiff')