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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 SummaryMetadata(self, run, tag):
 """Return the summary metadata for the given tag on the given run. Args: run: A string name of the run for which summary metadata is to be retrieved. tag: A string name of the tag whose summary metadata is to be retrieved. Raises: KeyError: If the run is not found, or the tag is not available for the given run. Returns: A `SummaryMetadata` protobuf. """

    accumulator = self.GetAccumulator(run)
    return accumulator.SummaryMetadata(tag)