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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 get_output(self):
 """ Override standard get_output to return xml-file if xml-file is specified. Otherwise, will return database. """

    if self.__xml_output:
      return self.__xml_output
    elif self.get_database():
      return self.get_database()
    else:
      raise ValueError, "no output xml file or database specified"