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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def is_validated(self):
 """ Returns True if this instance is validated. Note that resolving this property requires a DB query, so if you've a very large amount of receipts you should prefetch (see django's ``select_related``) the ``validation`` field. Even so, a DB query *may* be triggered. If you need a large list of validated receipts, you should actually filter them via a QuerySet:: Receipt.objects.filter(validation__result==RESULT_APPROVED) :rtype: bool """

        # Avoid the DB lookup if possible:
        if not self.receipt_number:
            return False

        try:
            return self.validation.result == ReceiptValidation.RESULT_APPROVED
        except ReceiptValidation.DoesNotExist:
            return False