def METHOD_NAME(self, section_label, section_number):
    super(IntrastatStatementPurchaseSection2, self).METHOD_NAME(
        section_label, section_number
    )
    if not self.year_id:
        raise ValidationError(
            _("Missing reference year on 'Purchases - Section 2'")
        )
    if not self.sign_variation:
        raise ValidationError(
            _("Missing adjustment sign on 'Purchases - Section 2'")
        )
    if self.statement_id.period_type == "M":
        if not self.month:
            raise ValidationError(
                _(
                    "Missing reference month "
                    "on 'Purchases - Section 2' adjustment"
                )
            )
    elif self.statement_id.period_type == "T":
        if not self.quarterly:
            raise ValidationError(
                _(
                    "Missing reference quarter "
                    "on 'Purchases - Section 2' adjustment"
                )
            )