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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 iteritems(self, prefix=None):
 """Like dict.iteritems."""

        query = Setting.query
        if prefix:
            query = query.filter(Setting.key.startswith(prefix))

        for s in query.yield_per(1000):
            yield (s.key, s.value)