import sys

def outer():
    x = 0

    def traced_looper():
        # Force w_locals to be instantiated (only matters on PyPy; on CPython
        # you can comment this line out and everything stays the same)
        locals()
        # Force x to be closed over (could use 'nonlocal' on py3)
        if False:
            x

    yield traced_looper
    while True:
        x += 1
        yield "value of x is: %d" % (x,)

outer_generator = outer()
traced_looper = outer_generator.next()


def tracefunc(frame, event, arg):
    print(outer_generator.next())
    return tracefunc

sys.settrace(tracefunc)
traced_looper()
sys.settrace(None)