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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 _cursor_down(self, value):
 """ Moves the cursor down by ``value``. """

        self._cursor.clearSelection()
        if self._cursor.atEnd():
            self._cursor.insertText('\n')
        else:
            self._cursor.movePosition(self._cursor.Down, self._cursor.MoveAnchor, value)
        self._last_cursor_pos = self._cursor.position()