def draw(self, points, can=None):
        """Parameter <points> specifies the
        list of points the arrow traverses through.
        It should contain at least two points, i.e.,
        the tail and tip. Parameter
        <can> is an optional parameter that specifies the output.
        <<canvas>>
        """
        if can == None: can = canvas.default_canvas()
        assert self.check_integrity()
        xtip = points[-1][0]
        ytip = points[-1][1]

        xtail = points[-2][0]
        ytail = points[-2][1]

        can.newpath()
        can.set_line_style(self.line_style)
        if len(points) > 2:
            can.moveto(points[0][0], points[0][1])
            for i in range(1, len(points) - 1):
                can.lineto(points[i][0], points[i][1])

        draw_arrowbody(can, xscale(xtail), yscale(ytail),
                       yscale(xtip), yscale(ytip),
                       nscale(self.head_len))

        can.set_fill_color(self.head_color)
        draw_arrowhead(can, xscale(xtail), yscale(ytail),
                       xscale(xtip), yscale(ytip),
                       nscale(self.thickness),
                       nscale(self.head_len),
                       self.head_style)

        can.setbb(xtail, ytail)
        can.setbb(xtip, ytip)
Parameter <points> specifies the
        list of points the arrow traverses through.
        It should contain at least two points, i.e.,
        the tail and tip. Parameter
        <can> is an optional parameter that specifies the output.
        <<canvas>>