Best practice for Python & Django constants

It is quite common to define constants for the integer values as follows:

class Task(models.Model):
    CANCELLED = -1
    REQUIRES_ATTENTION = 0
    WORK_IN_PROGRESS = 1
    COMPLETE = 2

    Status = (
        (CANCELLED, 'Cancelled'),
        (REQUIRES_ATTENTION, 'Requires attention'),
        (WORK_IN_PROGRESS, 'Work in progress'),
        (COMPLETE, 'Complete'),
    )

    status = models.IntegerField(choices=Status, default=REQUIRES_ATTENTION)

By moving the constants and Status inside the model class, you keep the module’s namespace cleaner, and as a bonus you can refer to Task.COMPLETE wherever you import the Task model.