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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 GetProcessedTaskIdentifiers(self):
 """Identifiers for tasks which have been processed. Returns: list[str]: task identifiers that are processed. Raises: IOError: if the storage type is not supported or if the temporary path for the task storage does not exist. OSError: if the storage type is not supported or if the temporary path for the task storage does not exist. """

    if self._storage_type != definitions.STORAGE_TYPE_SESSION:
      raise IOError('Unsupported storage type.')

    if not self._processed_task_storage_path:
      raise IOError('Missing processed task storage path.')

    return [
        path.replace('.plaso', '')
        for path in os.listdir(self._processed_task_storage_path)]