def add_arrow ( self , x1 , y1 , x2 , y2 , * * kws ) : self . panel . add_arrow ( x1 , y1 , x2 , y2 , * * kws )
python how to use spines to draw the axes with arrow
add arrow to plot
def add_arrow(self, x1, y1, x2, y2, **kws):
        """add arrow to plot"""
        self.panel.add_arrow(x1, y1, x2, y2, **kws)