<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def data_changed(self, change):
 """ Notify the model that data has changed in this cell! """

        index = self.index
        if index:
            self.view.model.dataChanged.emit(index, index)