How to use the yappi.set_context_name_callback function in yappi

def test_clear_callback(self):
        self.callback_count = 0

        def callback():
            self.callback_count += 1
            return 'name'

        yappi.set_context_name_callback(callback)
        yappi.start()
        a()
        yappi.set_context_name_callback(None)
        old_callback_count = self.callback_count
        a()
        yappi.stop()

        self.assertEqual(old_callback_count, self.callback_count)

def tearDown(self):
        yappi.set_context_name_callback(None)
        super(ContextNameCallbackTest, self).tearDown()

def test_clear_callback(self):
        self.callback_count = 0

        def callback():
            self.callback_count += 1
            return 'name'

        yappi.set_context_name_callback(callback)
        yappi.start()
        a()
        yappi.set_context_name_callback(None)
        old_callback_count = self.callback_count
        a()
        yappi.stop()

        self.assertEqual(old_callback_count, self.callback_count)

def test_callback(self):
        self.context_id = 0
        self.context_name = 'a'
        yappi.set_context_id_callback(lambda: self.context_id)
        yappi.set_context_name_callback(lambda: self.context_name)
        yappi.start()
        a()
        self.context_id = 1
        self.context_name = 'b'
        a()

        # Re-schedule context 0.
        self.context_id = 0
        self.context_name = 'a'
        a()
        yappi.stop()

        threadstats = yappi.get_thread_stats().sort('name', 'ascending')
        self.assertEqual(2, len(threadstats))
        self.assertEqual(0, threadstats[0].id)
        self.assertEqual('a', threadstats[0].name)

def setUp(self):
        # reset everything back to default
        yappi.stop()
        yappi.clear_stats()
        yappi.set_clock_type('cpu')  # reset to default clock type
        yappi.set_context_id_callback(None)
        yappi.set_context_name_callback(None)
        yappi.set_tag_callback(None)

def test_callback_error(self):
        self.callback_count = 0

        def callback():
            self.callback_count += 1
            raise Exception('callback error')

        yappi.set_context_name_callback(callback)
        yappi.start()
        a()
        a()
        yappi.stop()

        # Callback was cleared after first error.
        self.assertEqual(1, self.callback_count)

def test_callback_non_string(self):
        self.callback_count = 0

        def callback():
            self.callback_count += 1
            return 1  # Supposed to return a string.

        yappi.set_context_name_callback(callback)
        yappi.start()
        a()
        a()
        yappi.stop()

        # Callback was cleared after first error.
        self.assertEqual(1, self.callback_count)

def test_bad_input(self):
        self.assertRaises(TypeError, yappi.set_context_name_callback, 1)

def _capture_profile(fname=''):
    if not fname:
        yappi.set_clock_type('cpu')
        # We need to set context to greenlet to profile greenlets
        # https://bitbucket.org/sumerc/yappi/pull-requests/3
        yappi.set_context_id_callback(
            lambda: id(greenlet.getcurrent()))
        yappi.set_context_name_callback(
            lambda: greenlet.getcurrent().__class__.__name__)
        yappi.start()
    else:
        yappi.stop()
        stats = yappi.get_func_stats()
        # User should provide filename. This file with a suffix .prof
        # will be created in temp directory.
        try:
            stats_file = os.path.join(tempfile.gettempdir(), fname + '.prof')
            stats.save(stats_file, "pstat")
        except Exception as e:
            print("Error while saving the trace stats ", str(e))
        finally:
            yappi.clear_stats()