code: def setCurrentIndex(self, index):
          
          if 0 <= index and index < len(self._stack):
              self._blockStack = True
              self._index = index
              self.emitCurrentChanged()
              self._blockStack = False
              return True
          return False
docs: Sets the current index for the history stack.
          
          :param      index | <int>
          
          :return     <bool> | success