media: refactor sound_node, introduce camera_node

12 files changed, 743 insertions, 0 deletions

diff --git a/test/__init__.py b/test/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/test/__init__.py
diff --git a/test/test.py b/test/test.py
new file mode 100755
index 0000000..7ea37e6
--- /dev/null
+++ b/test/test.py
@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+from home.relay import RelayClient
+
+
+if __name__ == '__main__':
+    c = RelayClient()
+    print(c, c._host)
\ No newline at end of file
diff --git a/test/test_amixer.py b/test/test_amixer.py
new file mode 100755
index 0000000..c8bd546
--- /dev/null
+++ b/test/test_amixer.py
@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+import sys, os.path
+sys.path.extend([
+    os.path.realpath(os.path.join(os.path.dirname(os.path.join(__file__)), '..')),
+])
+
+from argparse import ArgumentParser
+from src.home.config import config
+from src.home.audio import amixer
+
+
+def validate_control(input: str):
+    for control in config['amixer']['controls']:
+        if control['name'] == input:
+            return
+    raise ValueError(f'invalid control name: {input}')
+
+
+if __name__ == '__main__':
+    parser = ArgumentParser()
+    parser.add_argument('--get-all', action='store_true')
+    parser.add_argument('--mute', type=str)
+    parser.add_argument('--unmute', type=str)
+    parser.add_argument('--cap', type=str)
+    parser.add_argument('--nocap', type=str)
+    parser.add_argument('--get', type=str)
+    parser.add_argument('--incr', type=str)
+    parser.add_argument('--decr', type=str)
+    # parser.add_argument('--dump-config', action='store_true')
+
+    args = config.load('test_amixer', parser=parser)
+
+    # if args.dump_config:
+    #     print(config.data)
+    #     sys.exit()
+
+    if args.get_all:
+        for control in amixer.get_all():
+            print(f'control = {control["name"]}')
+            for line in control['info'].split('\n'):
+                print(f'    {line}')
+            print()
+        sys.exit()
+
+    if args.get:
+        info = amixer.get(args.get)
+        print(info)
+        sys.exit()
+
+    for action in ['incr', 'decr']:
+        if hasattr(args, action):
+            control = getattr(args, action)
+            if control is None:
+                continue
+
+            print(f'attempting to {action} {control}')
+            validate_control(control)
+            func = getattr(amixer, action)
+            try:
+                func(control, step=5)
+            except amixer.AmixerError as e:
+                print('error: ' + str(e))
+            sys.exit()
+
+    for action in ['mute', 'unmute', 'cap', 'nocap']:
+        if hasattr(args, action):
+            control = getattr(args, action)
+            if control is None:
+                continue
+
+            print(f"attempting to {action} {control}")
+
+            validate_control(control)
+            func = getattr(amixer, action)
+            try:
+                func(control)
+            except amixer.AmixerError as e:
+                print('error: ' + str(e))
+            sys.exit()
diff --git a/test/test_api.py b/test/test_api.py
new file mode 100755
index 0000000..959b2b3
--- /dev/null
+++ b/test/test_api.py
@@ -0,0 +1,11 @@
+#!/usr/bin/env python3
+from home.api import WebAPIClient
+from home.api.types import BotType
+from home.config import config
+
+
+if __name__ == '__main__':
+    config.load('test_api')
+
+    api = WebAPIClient()
+    print(api.log_bot_request(BotType.ADMIN, 1, "test_api.py"))
diff --git a/test/test_esp32_cam.py b/test/test_esp32_cam.py
new file mode 100755
index 0000000..27ce379
--- /dev/null
+++ b/test/test_esp32_cam.py
@@ -0,0 +1,56 @@
+#!/usr/bin/env python3
+import sys
+import os.path
+sys.path.extend([
+    os.path.realpath(
+        os.path.join(os.path.dirname(os.path.join(__file__)), '..')
+    )
+])
+
+from pprint import pprint
+from argparse import ArgumentParser
+from time import sleep
+from src.home.util import parse_addr
+from src.home.camera import esp32
+from src.home.config import config
+
+if __name__ == '__main__':
+    parser = ArgumentParser()
+    parser.add_argument('--addr', type=str, required=True,
+                        help='camera server address, in host:port format')
+    parser.add_argument('--status', action='store_true',
+                        help='print status and exit')
+
+    arg = config.load(False, parser=parser)
+    cam = esp32.WebClient(addr=parse_addr(arg.addr))
+
+    if arg.status:
+        status = cam.getstatus()
+        pprint(status)
+        sys.exit(0)
+
+    if cam.syncsettings(dict(
+        vflip=True,
+        hmirror=True,
+        framesize=esp32.FrameSize.SVGA_800x600,
+        lenc=True,
+        wpc=False,
+        bpc=False,
+        raw_gma=False,
+        agc=True,
+        gainceiling=5,
+        quality=10,
+        awb_gain=False,
+        awb=True,
+        aec_dsp=True,
+        aec=True
+    )) is True:
+        print('some settings were changed, sleeping for 0.5 sec')
+        sleep(0.5)
+
+    # cam.setdelay(200)
+
+    cam.setflash(True)
+    sleep(0.2)
+    cam.capture('/tmp/capture.jpg')
+    cam.setflash(False)
diff --git a/test/test_inverter_monitor.py b/test/test_inverter_monitor.py
new file mode 100755
index 0000000..cbf1b82
--- /dev/null
+++ b/test/test_inverter_monitor.py
@@ -0,0 +1,376 @@
+#!/usr/bin/env python3
+import cmd
+import time
+import logging
+import socket
+import sys
+import threading
+import os.path
+sys.path.extend([
+    os.path.realpath(
+        os.path.join(os.path.dirname(os.path.join(__file__)), '..')
+    )
+])
+
+from enum import Enum, auto
+from typing import Optional
+from src.home.util import stringify
+from src.home.config import config
+from src.home.inverter import (
+    wrapper_instance as inverter,
+
+    InverterMonitor,
+    ChargingEvent,
+    BatteryState,
+    BatteryPowerDirection,
+)
+
+
+def monitor_charging(event: ChargingEvent, **kwargs) -> None:
+    msg = 'event: ' + event.name
+    if event == ChargingEvent.AC_CURRENT_CHANGED:
+        msg += f' (current={kwargs["current"]})'
+    evt_logger.info(msg)
+
+
+def monitor_battery(state: BatteryState, v: float, load_watts: int) -> None:
+    evt_logger.info(f'bat: {state.name}, v: {v}, load_watts: {load_watts}')
+
+
+def monitor_error(error: str) -> None:
+    evt_logger.warning('error: ' + error)
+
+
+class InverterTestShell(cmd.Cmd):
+    intro = 'Welcome to the test shell. Type help or ? to list commands.\n'
+    prompt = '(test) '
+    file = None
+
+    def do_connect_ac(self, arg):
+        server.connect_ac()
+
+    def do_disconnect_ac(self, arg):
+        server.disconnect_ac()
+
+    def do_pd_charge(self, arg):
+        server.set_pd(BatteryPowerDirection.CHARGING)
+
+    def do_pd_nothing(self, arg):
+        server.set_pd(BatteryPowerDirection.DO_NOTHING)
+
+    def do_pd_discharge(self, arg):
+        server.set_pd(BatteryPowerDirection.DISCHARGING)
+
+
+class ChargerMode(Enum):
+    NONE = auto()
+    CHARGING = auto()
+
+
+class ChargerEmulator(threading.Thread):
+    def __init__(self):
+        super().__init__()
+        self.setName('ChargerEmulator')
+
+        self.logger = logging.getLogger('charger')
+        self.interrupted = False
+        self.mode = ChargerMode.NONE
+
+        self.pd = None
+        self.ac_connected = False
+        self.mppt_connected = False
+
+    def run(self):
+        while not self.interrupted:
+            if self.pd == BatteryPowerDirection.CHARGING\
+                    and self.ac_connected\
+                    and not self.mppt_connected:
+
+                v = server._get_voltage() + 0.02
+                self.logger.info('incrementing voltage')
+                server.set_voltage(v)
+
+            time.sleep(2)
+
+    def stop(self):
+        self.interrupted = True
+
+    def setmode(self, mode: ChargerMode):
+        self.mode = mode
+
+    def ac_changed(self, connected: bool):
+        self.ac_connected = connected
+
+    def mppt_changed(self, connected: bool):
+        self.mppt_connected = connected
+
+    def current_changed(self, amps):
+        # FIXME
+        # this method is not being called and voltage is not changing]
+        # when current changes
+        v = None
+        if amps == 2:
+            v = 49
+        elif amps == 10:
+            v = 51
+        elif amps == 20:
+            v = 52.5
+        elif amps == 30:
+            v = 53.5
+        elif amps == 40:
+            v = 54.5
+        if v is not None:
+            self.logger.info(f'setting voltage {v}')
+            server.set_voltage(v)
+
+    def pd_changed(self, pd: BatteryPowerDirection):
+        self.pd = pd
+
+
+class InverterEmulator(threading.Thread):
+    def __init__(self, host: str, port: int):
+        super().__init__()
+        self.setName('InverterEmulatorServer')
+        self.lock = threading.Lock()
+
+        self.status = {"grid_voltage": {"unit": "V", "value": 0.0},
+                       "grid_freq": {"unit": "Hz", "value": 0.0},
+                       "ac_output_voltage": {"unit": "V", "value": 230.0},
+                       "ac_output_freq": {"unit": "Hz", "value": 50.0},
+                       "ac_output_apparent_power": {"unit": "VA", "value": 92},
+                       "ac_output_active_power": {"unit": "Wh", "value": 30},
+                       "output_load_percent": {"unit": "%", "value": 1},
+                       "battery_voltage": {"unit": "V", "value": 48.4},
+                       "battery_voltage_scc": {"unit": "V", "value": 0.0},
+                       "battery_voltage_scc2": {"unit": "V", "value": 0.0},
+                       "battery_discharging_current": {"unit": "A", "value": 0},
+                       "battery_charging_current": {"unit": "A", "value": 0},
+                       "battery_capacity": {"unit": "%", "value": 62},
+                       "inverter_heat_sink_temp": {"unit": "°C", "value": 8},
+                       "mppt1_charger_temp": {"unit": "°C", "value": 0},
+                       "mppt2_charger_temp": {"unit": "°C", "value": 0},
+                       "pv1_input_power": {"unit": "Wh", "value": 0},
+                       "pv2_input_power": {"unit": "Wh", "value": 0},
+                       "pv1_input_voltage": {"unit": "V", "value": 0.0},
+                       "pv2_input_voltage": {"unit": "V", "value": 0.0},
+                       "configuration_status": "Default",
+                       "mppt1_charger_status": "Abnormal",
+                       "mppt2_charger_status": "Abnormal",
+                       "load_connected": "Connected",
+                       "battery_power_direction": "Discharge",
+                       "dc_ac_power_direction": "DC/AC",
+                       "line_power_direction": "Do nothing",
+                       "local_parallel_id": 0}
+        self.rated = {"ac_input_rating_voltage": {"unit": "V", "value": 230.0},
+                      "ac_input_rating_current": {"unit": "A", "value": 21.7},
+                      "ac_output_rating_voltage": {"unit": "V", "value": 230.0},
+                      "ac_output_rating_freq": {"unit": "Hz", "value": 50.0},
+                      "ac_output_rating_current": {"unit": "A", "value": 21.7},
+                      "ac_output_rating_apparent_power": {"unit": "VA", "value": 5000},
+                      "ac_output_rating_active_power": {"unit": "Wh", "value": 5000},
+                      "battery_rating_voltage": {"unit": "V", "value": 48.0},
+                      "battery_recharge_voltage": {"unit": "V", "value": 51.0},
+                      "battery_redischarge_voltage": {"unit": "V", "value": 58.0},
+                      "battery_under_voltage": {"unit": "V", "value": 42.0},
+                      "battery_bulk_voltage": {"unit": "V", "value": 57.6},
+                      "battery_float_voltage": {"unit": "V", "value": 54.0},
+                      "battery_type": "User",
+                      "max_charging_current": {"unit": "A", "value": 60},
+                      "max_ac_charging_current": {"unit": "A", "value": 10},
+                      "input_voltage_range": "Appliance",
+                      "output_source_priority": "Parallel output",
+                      "charge_source_priority": "Solar-and-Utility",
+                      "parallel_max_num": 6,
+                      "machine_type": "Off-Grid-Tie",
+                      "topology": "Transformer-less",
+                      "output_model_setting": "Single module",
+                      "solar_power_priority": "Load-Battery-Utility",
+                      "mppt": "2"}
+
+        self.host = host
+        self.port = port
+        self.interrupted = False
+        self.logger = logging.getLogger('srv')
+
+        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        self.sock.bind((self.host, self.port))
+
+    def run(self):
+        self.sock.listen(5)
+
+        while not self.interrupted:
+            conn, address = self.sock.accept()
+
+            alive = True
+            while alive:
+                try:
+                    buf = conn.recv(2048)
+                    message = buf.decode().strip()
+                except OSError as exc:
+                    self.logger.error('failed to recv()')
+                    self.logger.exception(exc)
+
+                    alive = False
+
+                    try:
+                        conn.close()
+                    except:
+                        pass
+
+                    continue  # exit the loop
+
+                self.logger.log(0, f'< {message}')
+
+                if message.strip() == '':
+                    continue
+
+                if message == 'format json':
+                    # self.logger.info(f'got {message}')
+                    self.reply_ok(conn)
+
+                elif message.startswith('exec '):
+                    command = message[5:].split()
+                    args = command[1:]
+                    command = command[0]
+
+                    if command == 'get-allowed-ac-charging-currents':
+                        self.reply_ok(conn, [2, 10, 20, 30, 40, 50, 60])
+                    elif command == 'get-status':
+                        self.reply_ok(conn, self._get_status())
+                    elif command == 'get-rated':
+                        self.reply_ok(conn, self._get_rated())
+                    elif command == 'set-max-ac-charging-current':
+                        self.set_ac_current(args[1])
+                        self.reply_ok(conn, 1)
+                    else:
+                        raise ValueError('unsupported command: ' + command)
+                else:
+                    raise ValueError('unexpected request: ' + message)
+
+    def reply_ok(self, connection, data=None):
+        buf = 'ok' + '\r\n'
+        if data:
+            if not isinstance(data, str):
+                data = stringify({'result': 'ok', 'data': data})
+            buf += data + '\r\n'
+        buf += '\r\n'
+        self.logger.log(0, f'> {buf.strip()}')
+        connection.sendall(buf.encode())
+
+    def _get_status(self) -> dict:
+        with self.lock:
+            return self.status
+
+    def _get_rated(self) -> dict:
+        with self.lock:
+            return self.rated
+
+    def _get_voltage(self) -> float:
+        with self.lock:
+            return self.status['battery_voltage']['value']
+
+    def stop(self):
+        self.interrupted = True
+        self.sock.close()
+
+    def connect_ac(self):
+        with self.lock:
+            self.status['grid_voltage']['value'] = 230
+            self.status['grid_freq']['value'] = 50
+        charger.ac_changed(True)
+
+    def disconnect_ac(self):
+        with self.lock:
+            self.status['grid_voltage']['value'] = 0
+            self.status['grid_freq']['value'] = 0
+            #self.status['battery_voltage']['value'] = 48.4  # revert to initial value
+        charger.ac_changed(False)
+
+    def connect_mppt(self):
+        with self.lock:
+            self.status['pv1_input_power']['value'] = 1
+            self.status['pv1_input_voltage']['value'] = 50
+            self.status['mppt1_charger_status'] = 'Charging'
+        charger.mppt_changed(True)
+
+    def disconnect_mppt(self):
+        with self.lock:
+            self.status['pv1_input_power']['value'] = 0
+            self.status['pv1_input_voltage']['value'] = 0
+            self.status['mppt1_charger_status'] = 'Abnormal'
+        charger.mppt_changed(False)
+
+    def set_voltage(self, v: float):
+        with self.lock:
+            self.status['battery_voltage']['value'] = v
+
+    def set_ac_current(self, amps):
+        with self.lock:
+            self.rated['max_ac_charging_current']['value'] = amps
+        charger.current_changed(amps)
+
+    def set_pd(self, pd: BatteryPowerDirection):
+        if pd == BatteryPowerDirection.CHARGING:
+            val = 'Charge'
+        elif pd == BatteryPowerDirection.DISCHARGING:
+            val = 'Discharge'
+        else:
+            val = 'Do nothing'
+        with self.lock:
+            self.status['battery_power_direction'] = val
+        charger.pd_changed(pd)
+
+
+logger = logging.getLogger(__name__)
+evt_logger = logging.getLogger('evt')
+server: Optional[InverterEmulator] = None
+charger: Optional[ChargerEmulator] = None
+
+
+def main():
+    global server, charger
+
+    # start fake inverterd server
+    try:
+        server = InverterEmulator(host=config['inverter']['host'],
+                                  port=config['inverter']['port'])
+        server.start()
+    except OSError as e:
+        logger.error('failed to start server')
+        logger.exception(e)
+        return
+    logger.info('server started')
+
+    # start charger thread
+    charger = ChargerEmulator()
+    charger.start()
+
+    # init inverterd wrapper
+    inverter.init(host=config['inverter']['host'],
+                  port=config['inverter']['port'])
+
+    # start monitor
+    mon = InverterMonitor()
+    mon.set_charging_event_handler(monitor_charging)
+    mon.set_battery_event_handler(monitor_battery)
+    mon.set_error_handler(monitor_error)
+    mon.start()
+    logger.info('monitor started')
+
+    try:
+        InverterTestShell().cmdloop()
+
+        server.join()
+        mon.join()
+        charger.join()
+
+    except KeyboardInterrupt:
+        server.stop()
+        mon.stop()
+        charger.stop()
+
+
+if __name__ == '__main__':
+    config.load('test_inverter_monitor')
+    main()
diff --git a/test/test_record_upload.py b/test/test_record_upload.py
new file mode 100755
index 0000000..a0c3faf
--- /dev/null
+++ b/test/test_record_upload.py
@@ -0,0 +1,88 @@
+#!/usr/bin/env python3
+import logging
+import sys
+import os.path
+sys.path.extend([
+    os.path.realpath(
+        os.path.join(os.path.dirname(os.path.join(__file__)), '..', '..')
+    )
+])
+
+import time
+
+from src.home.api import WebAPIClient, RequestParams
+from src.home.config import config
+from src.home.media import SoundRecordClient
+from src.home.util import parse_addr
+
+logger = logging.getLogger(__name__)
+
+
+# record callbacks
+# ----------------
+
+def record_error(info: dict, userdata: dict):
+    node = userdata['node']
+    # TODO
+
+
+def record_finished(info: dict, fn: str, userdata: dict):
+    logger.info('record finished: ' + str(info))
+
+    node = userdata['node']
+    api.upload_recording(fn, node, info['id'], int(info['start_time']), int(info['stop_time']))
+
+
+# api client callbacks
+# --------------------
+
+def api_error_handler(exc, name, req: RequestParams):
+    if name == 'upload_recording':
+        logger.error('failed to upload recording, exception below')
+        logger.exception(exc)
+
+    else:
+        logger.error(f'api call ({name}, params={req.params}) failed, exception below')
+        logger.exception(exc)
+
+
+def api_success_handler(response, name, req: RequestParams):
+    if name == 'upload_recording':
+        node = req.params['node']
+        rid = req.params['record_id']
+
+        logger.debug(f'successfully uploaded recording (node={node}, record_id={rid}), api response:' + str(response))
+
+        # deleting temp file
+        try:
+            os.unlink(req.files['file'])
+        except OSError as exc:
+            logger.error(f'error while deleting temp file:')
+            logger.exception(exc)
+
+        record.forget(node, rid)
+
+
+if __name__ == '__main__':
+    config.load('test_record_upload')
+
+    nodes = {}
+    for name, addr in config['nodes'].items():
+        nodes[name] = parse_addr(addr)
+    record = SoundRecordClient(nodes,
+                               error_handler=record_error,
+                               finished_handler=record_finished,
+                               download_on_finish=True)
+
+    api = WebAPIClient()
+    api.enable_async(error_handler=api_error_handler,
+                     success_handler=api_success_handler)
+
+    record_id = record.record('localhost', 3, {'node': 'localhost'})
+    print(f'record_id: {record_id}')
+
+    while True:
+        try:
+            time.sleep(0.1)
+        except (KeyboardInterrupt, SystemExit):
+            break
\ No newline at end of file
diff --git a/test/test_send_fake_sound_hit.py b/test/test_send_fake_sound_hit.py
new file mode 100755
index 0000000..9660c45
--- /dev/null
+++ b/test/test_send_fake_sound_hit.py
@@ -0,0 +1,25 @@
+#!/usr/bin/env python3
+import sys
+import os.path
+sys.path.extend([
+    os.path.realpath(
+        os.path.join(os.path.dirname(os.path.join(__file__)), '..')
+    )
+])
+
+from argparse import ArgumentParser
+from src.home.util import send_datagram, stringify, parse_addr
+
+
+if __name__ == '__main__':
+    parser = ArgumentParser()
+    parser.add_argument('--name', type=str, required=True,
+                        help='node name, like `diana`')
+    parser.add_argument('--hits', type=int, required=True,
+                        help='hits count')
+    parser.add_argument('--server', type=str, required=True,
+                        help='center server addr in host:port format')
+
+    args = parser.parse_args()
+
+    send_datagram(stringify([args.name, args.hits]), parse_addr(args.server))
diff --git a/test/test_sensors_plot.py b/test/test_sensors_plot.py
new file mode 100755
index 0000000..e69de29
--- /dev/null
+++ b/test/test_sensors_plot.py
diff --git a/test/test_sound_node_client.py b/test/test_sound_node_client.py
new file mode 100755
index 0000000..16feb78
--- /dev/null
+++ b/test/test_sound_node_client.py
@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+import sys, os.path
+sys.path.extend([
+    os.path.realpath(os.path.join(os.path.dirname(os.path.join(__file__)), '..')),
+])
+
+from src.home.api.errors import ApiResponseError
+from src.home.media import SoundNodeClient
+
+
+if __name__ == '__main__':
+    client = SoundNodeClient(('127.0.0.1', 8313))
+    print(client.amixer_get_all())
+
+    try:
+        client.amixer_get('invalidname')
+    except ApiResponseError as exc:
+        print(exc)
+
diff --git a/test/test_sound_server_api.py b/test/test_sound_server_api.py
new file mode 100755
index 0000000..1b4eb8b
--- /dev/null
+++ b/test/test_sound_server_api.py
@@ -0,0 +1,66 @@
+#!/usr/bin/env python3
+import sys
+import os.path
+sys.path.extend([
+    os.path.realpath(
+        os.path.join(os.path.dirname(os.path.join(__file__)), '..')
+    )
+])
+import threading
+
+from time import sleep
+from src.home.config import config
+from src.home.api import WebAPIClient
+from src.home.api.types import SoundSensorLocation
+
+interrupted = False
+
+
+class HitCounter:
+    def __init__(self):
+        self.sensors = {}
+        self.lock = threading.Lock()
+        self._reset_sensors()
+
+    def _reset_sensors(self):
+        for loc in SoundSensorLocation:
+            self.sensors[loc.name.lower()] = 0
+
+    def add(self, name: str, hits: int):
+        if name not in self.sensors:
+            raise ValueError(f'sensor {name} not found')
+
+        with self.lock:
+            self.sensors[name] += hits
+
+    def get_all(self) -> list[tuple[str, int]]:
+        vals = []
+        with self.lock:
+            for name, hits in self.sensors.items():
+                if hits > 0:
+                    vals.append((name, hits))
+            self._reset_sensors()
+        return vals
+
+
+def hits_sender():
+    while True:
+        try:
+            all_hits = hc.get_all()
+            if all_hits:
+                api.add_sound_sensor_hits(all_hits)
+            sleep(5)
+        except (KeyboardInterrupt, SystemExit):
+            return
+
+
+if __name__ == '__main__':
+    config.load('test_api')
+
+    hc = HitCounter()
+    api = WebAPIClient()
+
+    hc.add('spb1', 1)
+    # hc.add('big_house', 123)
+
+    hits_sender()
diff --git a/test/test_stopwatch.py b/test/test_stopwatch.py
new file mode 100755
index 0000000..6ff2c0e
--- /dev/null
+++ b/test/test_stopwatch.py
@@ -0,0 +1,16 @@
+from home.util import Stopwatch, StopwatchError
+from time import sleep
+
+
+if __name__ == '__main__':
+    s = Stopwatch()
+    s.go()
+    sleep(2)
+    s.pause()
+    s.go()
+    sleep(1)
+    print(s.get_elapsed_time())
+    sleep(1)
+    print(s.get_elapsed_time())
+    s.pause()
+    print(s.get_elapsed_time())