import matplotlib.pyplot as plt
import numpy as np
import arviz as az
plt.style.use('arviz-darkgrid')
x = np.linspace(-3, 3, 500)
ls = [0., -2]
us = [2., 1]
for l, u in zip(ls, us):
    y = np.zeros(500)
    y[(x<u) & (x>l)] = 1.0/(u-l)
    plt.plot(x, y, label='lower = {}, upper = {}'.format(l, u))
plt.xlabel('x', fontsize=12)
plt.ylabel('f(x)', fontsize=12)
plt.ylim(0, 1)
plt.legend(loc=1)
plt.show()