name 'fullname' is not defined

[witch]

fullname is method of class Person, so you need to call it like this

person1.fullname()

you may want to print when call it

print(person1.fullname())

a bit advanced, would be to make it a property (not method). If it is too advanced, just ignore this for the moment

@property
def fullname(self):
    return '{} {} {}'.format(self.first, self.last, self.fathers_name)

if you do so, you will access it like this

person1.fullname

Thanks you helped me a lot ! I appericate it !