Update app.py

app.py

@@ -40,7 +40,7 @@ pred_std2 = 2 * (pred_var.diagonal() ** 0.5)
 
 ax.plot(x_test, pred_mean, label='predictive mean ($\\mu$)')
 ax.fill_between(x_test.ravel(), pred_mean.ravel()-pred_std2.ravel(), 
-                pred_mean.ravel()+pred_std2.ravel(), alpha=0.5, label='$$\\mu \\pm 2\\sigma$$')
+                pred_mean.ravel()+pred_std2.ravel(), alpha=0.5, label='$\\mu \\pm 2\\sigma$')
 ax.set_xlabel('x')
 ax.set_ylabel('y')
 ax.legend()