let t = []

def foo():
    let a, b, c = 1,2,3
    t.append(lambda: (a,b,c))
    yield
    a = 'a'
    t.append(lambda: (b,c,a))
    yield
    b = 'b'
    t.append(lambda: (c,b,a))
    yield
    c = 'c'

let g = foo()
print('one')
g()
print(t[0]())
if True:
    print('two')
    g()
print(t[0]())
print(t[1]())
print('three')
g()
print(t[0]())
print(t[1]())
print(t[2]())
print("exhaust")
g()

del g

import gc
gc.collect()
gc.collect()
gc.collect()
gc.collect()


print(t[0]())
print(t[1]())
print(t[2]())