How to use the whisper.update function in whisper

def test_diff(self):
        testdb = "test-%s" % self.filename

        now = int(time.time())

        self.addCleanup(self._remove, testdb)
        whisper.create(testdb, self.retention)

        whisper.create(self.filename, self.retention)

        whisper.update(testdb, 1.0, now)
        whisper.update(self.filename, 2.0, now)

        results = whisper.diff(testdb, self.filename)

        expected = [(0, [(int(now), 1.0, 2.0)], 1), (1, [], 0)]

        self.assertEqual(results, expected)

def test_file_diff(self):
        testdb = "test-%s" % self.filename

        now = time.time()

        self.addCleanup(self._remove, testdb)
        whisper.create(testdb, self.retention)

        whisper.create(self.filename, self.retention)

        whisper.update(testdb, 1.0, now)
        whisper.update(self.filename, 2.0, now)

        # Merging 2 archives with different retentions should fail
        with open(testdb, 'rb') as fh_1:
            with open(self.filename, 'rb+') as fh_2:
                results = whisper.file_diff(fh_1, fh_2)

        expected = [(0, [(int(now), 1.0, 2.0)], 1), (1, [], 0)]

        self.assertEqual(results, expected)

for i, (timestamp, value) in enumerate(data):
            # is value in the fetched data?
            self.assertEqual(value, fetch_data[i])

        # check TimestampNotCovered
        with AssertRaisesException(
                whisper.TimestampNotCovered(
                    'Timestamp not covered by any archives in this database.')):
            # in the futur
            whisper.update(self.filename, 1.337, time.time() + 1)

        with AssertRaisesException(
                whisper.TimestampNotCovered(
                    'Timestamp not covered by any archives in this database.')):
            # before the past
            whisper.update(self.filename, 1.337, time.time() - retention_schema[0][1] - 1)

        # When no timestamp is passed in, it should use the current time
        original_lock = whisper.LOCK
        whisper.LOCK = True
        whisper.update(self.filename, 3.7337, None)
        fetched = whisper.fetch(self.filename, 0)[1]
        self.assertEqual(fetched[-1], 3.7337)

        whisper.LOCK = original_lock

def test_diff(self):
        testdb = "test-%s" % self.filename

        now = int(time.time())

        self.addCleanup(self._remove, testdb)
        whisper.create(testdb, self.retention)

        whisper.create(self.filename, self.retention)

        whisper.update(testdb, 1.0, now)
        whisper.update(self.filename, 2.0, now)

        results = whisper.diff(testdb, self.filename)

        expected = [(0, [(int(now), 1.0, 2.0)], 1), (1, [], 0)]

        self.assertEqual(results, expected)

with AssertRaisesException(
                whisper.TimestampNotCovered(
                    'Timestamp not covered by any archives in this database.')):
            # in the futur
            whisper.update(self.filename, 1.337, time.time() + 1)

        with AssertRaisesException(
                whisper.TimestampNotCovered(
                    'Timestamp not covered by any archives in this database.')):
            # before the past
            whisper.update(self.filename, 1.337, time.time() - retention_schema[0][1] - 1)

        # When no timestamp is passed in, it should use the current time
        original_lock = whisper.LOCK
        whisper.LOCK = True
        whisper.update(self.filename, 3.7337, None)
        fetched = whisper.fetch(self.filename, 0)[1]
        self.assertEqual(fetched[-1], 3.7337)

        whisper.LOCK = original_lock

wsp = wsp or self.filename
        schema = schema or [(1, 20)]

        num_data_points = 20

        # create sample data
        self.addCleanup(self._remove, wsp)
        whisper.create(wsp, schema, sparse=sparse, useFallocate=useFallocate)
        tn = int(time.time()) - num_data_points

        data = []
        for i in range(num_data_points):
            data.append((tn + 1 + i, random.random() * 10))

        # test single update
        whisper.update(wsp, data[0][1], data[0][0])

        # test multi update
        whisper.update_many(wsp, data[1:])

        return data

def _update(self, datapoints):
        """
        This method store in the datapoints in the current database.

            :datapoints: is a list of tupple with the epoch timestamp and value
                 [(1368977629,10)]
        """
        if len(datapoints) == 1:
            timestamp, value = datapoints[0]
            whisper.update(self.path, value, timestamp)
        else:
            whisper.update_many(self.path, datapoints)