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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 BatchConvert(self, metadata_value_pairs, token=None):
 """Converts a batch of StatEntry value to ExportedFile values at once. Args: metadata_value_pairs: a list or a generator of tuples (metadata, value), where metadata is ExportedMetadata to be used for conversion and value is a StatEntry to be converted. token: Security token: Yields: Resulting ExportedFile values. Empty list is a valid result and means that conversion wasn't possible. """

    if data_store.RelationalDBEnabled():
      result_generator = self._BatchConvertRelational(metadata_value_pairs)
    else:
      result_generator = self._BatchConvertLegacy(
          metadata_value_pairs, token=token)

    for r in result_generator:
      yield r