docs: def write_uai(self, filename):
          """
          Write the xml data into the file.
  
          Parameters
          ----------
          filename: Name of the file.
  
          Examples
          -------
          >>> writer = UAIWriter(model)
          >>> writer.write_xmlbif(test_file)
          """
          writer = self.__str__()
          with open(filename, 'w') as fout:
              fout.write(writer)