import matplotlib.pylot as plt
x_coordinates = [1, 2, 3]
y1_coordinates = [1, 2, 3]
y2_coordinates = [3, 4, 5]
fig = plt.figure(1)
plt.plot(x_coordinates, y1_coordinates) # plot first line
plt.plot(x_coordinates, y2_coordinates) # plot second line
plt.show()