def before(x, y):
e1 = env_setitem(newenv, embed(x), x)
e1 = env_setitem(e1, embed(y), y)
e2 = env_setitem(newenv, embed(y), y)
e2 = env_setitem(e2, embed(x), x)
return env_getitem(env_add(e1, e2), embed(x), 0)
def f(x, y):
e1 = env_setitem(newenv, embed(x), 100)
e2 = env_setitem(newenv, embed(x), 10)
e2 = env_setitem(e2, embed(y), 20)
e3 = env_add(e1, e2)
a = env_getitem(e3, embed(x), 0)
b = env_getitem(e3, embed(y), 0)
c = env_getitem(e3, embed(a), 0)
return (a, b, c)