from actuarialmath import LifeTable

life = LifeTable().set_table(q={40: 0.25, 41: 1}).set_interest(i=0.05)
v = 1 / 1.05
print("Actual variance:", life.whole_life_insurance(40, moment=life.VARIANCE))
print("Independent variance:", 0.25 * 0.75 * (v - v * v) ** 2)