def METHOD_NAME(self):
    contours = [0.9, 0.5]
    for arr in [self.biarr, self.triarr]:
        for mode in ["density"]:
            with self.subTest(mode=mode, arr=arr):
                out = density(arr, mode=mode, contours=contours)
                self.assertTrue(isinstance(out, matplotlib.axes.Axes))
            plt.close("all")