User = get_user_model()

def populate_asset_assignee(apps, schema_editor):
    for user in User.objects.all():
        user.save()
        # Some more code

class User(AbstractUser):
    username = None
    email = models.EmailField(max_length=50, unique=True)
    cohort = models.IntegerField(blank=True, null=True)
    slack_handle = models.CharField(max_length=50,
                                blank=True, null=True)
    picture = models.CharField(max_length=255, blank=True, null=True)
    phone_number = models.CharField(max_length=50, blank=True, null=True)
    last_modified = models.DateTimeField(auto_now=True, editable=False)
    password = models.CharField(max_length=128, blank=True, null=True)
    location = models.ForeignKey('SomeCentre',
                            blank=False,
                            null=True,
                            on_delete=models.PROTECT)
    # Some more fields