How to use the hunter.Tracer function in hunter

def test_depth_limit(LineMatcher, tracer_impl, depth):
    buff = StringIO()
    from sample7 import one
    tracer = hunter.Tracer()
    predicate = When(Q(depth_lt=depth), CallPrinter(stream=buff))
    try:
        tracer.trace(predicate)
        one()
    finally:
        tracer.stop()
    output = buff.getvalue()
    lm = LineMatcher(output.splitlines())
    lm.fnmatch_lines([
        "* call      => one()",
        "* line         for i in range(1):  # one",
        "* line         two()",
        "* call         => two()",
        "* return       <= two: None",
        "* line         for i in range(1):  # one",
        "* return    <= one: None",

def tracing_wrapper(*args, **kwargs):
            # create the Tracer manually to avoid spending time in likely useless things like:
            # - loading PYTHONHUNTERCONFIG
            # - setting up the clear_env_var or thread_support options
            # - atexit cleanup registration
            with hunter.Tracer().trace(hunter.When(hunter.Query(**filters), *actions)):
                return func(*args, **kwargs)

def tracer_impl(request):
    if request.param == 'pure':
        Tracer = pytest.importorskip('hunter.tracer').Tracer
    elif request.param == 'cython':
        Tracer = pytest.importorskip('hunter._tracer').Tracer
    if Tracer is not hunter.Tracer:
        pytest.skip("Not %s in this environment" % Tracer)
    return Tracer

def test_proper_backend():
    if os.environ.get('PUREPYTHONHUNTER') or platform.python_implementation() == 'PyPy':
        assert 'hunter.tracer.Tracer' in repr(hunter.Tracer)
    else:
        assert 'hunter._tracer.Tracer' in repr(hunter.Tracer)

if is_unwrapped
                    else hunter.Query(
                        # Only trace lines...
                        kind="line",
                        # ...and only in the given function...
                        function=target_func_name,
                        # ...but we don't know how many times it's been wrapped.
                        # Use the module instead as an approximate match.
                        # This may catch other functions with the same name
                        # in the same module, but not much we can do about
                        # that without a custom Cython Query.
                        module_in=target_obj,
                    ),
                    hotspots,
                )
                tracer = hunter.Tracer(
                    # There's no need to call threading.settrace() because
                    # a) we're targeting a function we're about to call
                    #    in the same thread,
                    # b) we're going to undo it immediately after, and
                    # c) it would collide with other threads if they did
                    #    the same concurrently.
                    threading_support=False
                ).trace(predicate)
            else:
                tracer = None

            try:
                if instruments_by_event["call"] or instruments_by_event["return"]:
                    start = time.time()
                    _locals = {
                        "start": start,