import sys
import traceback

def func1():
    x = 1
    func2()

def func2():
    y = 2
    func3()

def func3():
    global err
    z = 3
    try:
        raise ValueError()
    except Exception as exc:
        err = exc

def dump_locals(tb):
    frame = tb.tb_frame
    main_frame = sys._getframe(1)
    print("locals:")
    while frame is not None:
        if frame is not main_frame:
            print("frame locals", frame.f_locals)
        frame = frame.f_back
    print()

err = None
func1()
tb = err.__traceback__

dump_locals(tb)

print("clear_frames()")
traceback.clear_frames(tb)
print()

dump_locals(tb)