i would like to know if its possible to have 2 classes (base=person and a child=user) where i have a property (email) nullable on base but it must be set for child class

```
class Person(models.Model):
    name = models.CharField(max_length=60, )
    identification = models.CharField(max_length=20, unique=True)
    email = models.CharField(max_length=60, null=True) #<~~~~ Email can be null

    def __str__():
        return self.name

class User(Person):
    email = models.CharField(max_length=60, ) #<~~~~ Email CAN'T be null

```

If i leave it like this i get this error:

```
django.core.exceptions.FieldError: Local field 'email' in class 'User' clashes with field of the same name from base class 'Person'.

```

Thanks.