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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 has_ist_trigger(self):
 """Return True if this BuildConfig has ImageStreamTag trigger."""

        triggers = self.template['spec'].get('triggers', [])
        if not triggers:
            return False
        for trigger in triggers:
            if trigger['type'] == 'ImageChange' and \
                    trigger['imageChange']['from']['kind'] == 'ImageStreamTag':
                return True
        return False