def f(t,y): return np.sin(t)+np.exp(-t)
def f_t(t,y): return np.cos(t)-np.exp(-t)
def f_y(t,y): return 0

t,y,h=0,0,0.5;
while t < 1+0.1*h:
    t, y = t+h, y + h*( (1+0.5*h*f_y(t,y))*f(t,y) + 0.5*h*f_t(t,y) );
    print t,y

0.5 0.5
1.0 1.0768595869306357
1.5 1.7030876580073921