'Adding a NOT NULL field to a model.'

def ask_not_null_addition(self, field_name, model_name):

    if (not self.dry_run):
        choice = self._choice_input(("You    are    trying    to    add    a    non-nullable    field    '%s'    to    %s    without    a    default;    we    can't    do    that    (the    database    needs    something    to    populate    existing    rows).\nPlease    select    a    fix:" % (field_name, model_name)), ['Provide    a    one-off    default    now    (will    be    set    on    all    existing    rows    with    a    null    value    for    this    column)', 'Quit,    and    let    me    add    a    default    in    models.py'])
        if (choice == 2):
            sys.exit(3)
        else:
            return self._ask_default()
    return None
