docs: def GetLastKey(self, voice=1):
          """key as in musical key, not index"""
  
          voice_obj = self.GetChild(voice)
          if voice_obj is not None:
              key = BackwardSearch(KeyNode, voice_obj, 1)
              if key is not None:
                  return key
              else:
                  if hasattr(self, "key"):
                      return self.key
          else:
              if hasattr(self, "key"):
                  return self.key