def METHOD_NAME(self):
    """
    Returns the order in which fields must appear on registration form
    """
    field_order = configuration_helpers.get_value('REGISTRATION_FIELD_ORDER')
    if not field_order:
        field_order = settings.REGISTRATION_FIELD_ORDER or self.EXTRA_FIELDS
    # Check that all of the EXTRA_FIELDS are in the field order and vice versa,
    # if not append missing fields at end of field order
    if set(self.EXTRA_FIELDS) != set(field_order):
        difference = set(self.EXTRA_FIELDS).difference(set(field_order))
        # sort the additional fields so we have could have a deterministic result
        # when presenting them
        field_order.extend(sorted(difference))
    return field_order