T0 = 300
sigma = 5.67E-08

def temp(T):
    return (715 - 0.4*sigma*(T**4-T0**4) + 32*T0)/32

print temp(301)

T = 301
while T-temp(T) != 0:
    T = temp(T)
    print T

def rk_2_step(T):
    return ?