如何理解创建QPen的参数
pen = (i*3, 20*1.3) #创建颜色的方法请参考： https://pyqtgraph.readthedocs.io/en/latest/functions.html#pyqtgraph.intColor
pen = (i*3, 20*1.3)
curve = pg.PlotCurveItem(pen=pen)
