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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_postgres(self):
 """ Determine if the running engine is postgres """

        if self._is_postgres_engine is None:
            is_postgres_engine = False
            try:
                dialect = self.session.bind.engine.name
                if 'redshift' in dialect or 'postg' in dialect or 'pg' in \
                        dialect:
                    is_postgres_engine = True
            except:
                pass
            self._is_postgres_engine = is_postgres_engine
        return self._is_postgres_engine