x_values = range(10)
y_values = [10, 12, 13, 13, 15, 19, 20, 22, 23, 29]
y_lower = [8, 10, 11, 11, 13, 17, 18, 20, 21, 27]
y_upper = [12, 14, 15, 15, 17, 21, 22, 24, 25, 31]
plt.fill_between(x_values, y_lower, y_upper, alpha=0.2) #this is the shaded error
plt.plot(x_values, y_values) #this is the line itself
plt.show()