How to use the hunter.trace function in hunter

def test_thread_filtering(LineMatcher, query):
    lines = StringIO()
    idents = set()
    names = set()
    started = threading.Event()

    def record(event):
        idents.add(event.threadid)
        names.add(event.threadname)
        return True

    with hunter.trace(~Q(**query), record,
                      actions=[CodePrinter(stream=lines), VarsPrinter('a', stream=lines), CallPrinter(stream=lines)],
                      threading_support=True):
        def foo(a=1):
            started.set()
            print(a)

        def main():
            foo()

        t = threading.Thread(target=foo)
        t.start()
        started.wait(10)
        main()

    lm = LineMatcher(lines.getvalue().splitlines())
    print(lines.getvalue())

def test_threading_support(LineMatcher):
    lines = StringIO()
    idents = set()
    names = set()
    started = threading.Event()

    def record(event):
        idents.add(event.threadid)
        names.add(event.threadname)
        return True

    with hunter.trace(record,
                      actions=[CodePrinter(stream=lines), VarsPrinter('a', stream=lines), CallPrinter(stream=lines)],
                      threading_support=True):
        def foo(a=1):
            started.set()
            print(a)

        def main():
            foo()

        t = threading.Thread(target=foo)
        t.start()
        started.wait(10)
        main()

    lm = LineMatcher(lines.getvalue().splitlines())
    assert idents - {t.ident} == {None}

def test_tracing_reinstall(LineMatcher):
    lines = StringIO()
    with hunter.trace(CodePrinter(stream=lines)):
        def foo():
            a = 2
            sys.settrace(sys.gettrace())
            a = 3

        def bar():
            a = 1
            foo()
            a = 4

        bar()
    print(lines.getvalue())
    lm = LineMatcher(lines.getvalue().splitlines())
    lm.fnmatch_lines([
        "*test_hunter.py:*   call              def bar():",
        "*test_hunter.py:*   line                  a = 1",

def test_debugger(LineMatcher):
    out = StringIO()
    calls = []

    class FakePDB:
        def __init__(self, foobar=1):
            calls.append(foobar)

        def set_trace(self, frame):
            calls.append(frame.f_code.co_name)

    with hunter.trace(
        lambda event: event.locals.get('node') == 'Foobar',
        module='test_hunter',
        function='foo',
        actions=[CodePrinter,
                 VarsPrinter('a', 'node', 'foo', 'test_debugger', stream=out),
                 Debugger(klass=FakePDB, foobar=2)]
    ):
        def foo():
            a = 1
            node = 'Foobar'
            node += 'x'
            a += 2
            return a

        foo()
    print(out.getvalue())

def test_trace_merge():
    with hunter.trace(function='a'):
        with hunter.trace(function='b'):
            with hunter.trace(function='c'):
                assert sys.gettrace().handler == When(Q(function='c'), CallPrinter)
            assert sys.gettrace().handler == When(Q(function='b'), CallPrinter)
        assert sys.gettrace().handler == When(Q(function='a'), CallPrinter)

def test_tracing_bare(LineMatcher):
    lines = StringIO()
    with hunter.trace(CodePrinter(stream=lines)):
        def a():
            return 1

        b = a()
        b = 2
        try:
            raise Exception('BOOM!')
        except Exception:
            pass
    print(lines.getvalue())
    lm = LineMatcher(lines.getvalue().splitlines())
    lm.fnmatch_lines([
        "*test_hunter.py* call              def a():",
        "*test_hunter.py* line                  return 1",
        "*test_hunter.py* return                return 1",
        "* ...       return value: 1",

def test_tracer_autostop():
    with hunter.trace(lambda: garbage) as tracer:
        if os.environ.get("SETUPPY_CFLAGS") == "-DCYTHON_TRACE=1":
            assert sys.gettrace() is not tracer
        else:
            assert sys.gettrace() is None

def __init__(self, *args, **kwargs):
        self._calls = []
        threading_support = kwargs.pop('threading_support', False)
        clear_env_var = kwargs.pop('clear_env_var', False)
        self.handler = hunter._prepare_predicate(*args, **kwargs)
        self._tracer = hunter.trace(self._append, threading_support=threading_support, clear_env_var=clear_env_var)

def test_examples():
    print("""
    CodePrinter
    """)
    with hunter.trace(stdlib=False, actions=[CodePrinter, VarsSnooper]):
        os.path.join(*map(str, range(10)))

    print("""
    CallPrinter
    """)
    with hunter.trace(stdlib=False, actions=[CallPrinter, VarsSnooper]):
        os.path.join(*map(str, range(10)))

def test_dump_exceptions(LineMatcher):
    stream = StringIO()
    with hunter.trace(stdlib=False, action=DumpExceptions(stream=stream)):
        silenced1()
        silenced2()
        silenced3()
        silenced4()

        print("Done silenced")
        try:
            notsilenced()
            print("Done not silenced")
        except ValueError:
            pass
    lm = LineMatcher(stream.getvalue().splitlines())
    lm.fnmatch_lines([
        '*>>>>>>>>>>>>>>>>>>>>>> tracing silenced1 on RuntimeError()',
        '*test_cookbook.py:***   exception         error()',
        '*                 ***   ...       exception value: *RuntimeError*',