How to use the pykka.actor.ThreadingActor function in pykka

from pykka.actor import ThreadingActor
from pykka.registry import ActorRegistry

from mopidy.mixers.base import BaseMixer
from mopidy.gstreamer import GStreamer

class GStreamerSoftwareMixer(ThreadingActor, BaseMixer):
    """Mixer which uses GStreamer to control volume in software."""

    def __init__(self):
        super(GStreamerSoftwareMixer, self).__init__()
        self.output = None

    def on_start(self):
        output_refs = ActorRegistry.get_by_class(GStreamer)
        assert len(output_refs) == 1, 'Expected exactly one running output.'
        self.output = output_refs[0].proxy()

    def get_volume(self):
        return self.output.get_volume().get()

    def set_volume(self, volume):
        self.output.set_volume(volume).get()

from pykka.actor import ThreadingActor

from mopidy.mixers.base import BaseMixer

class DummyMixer(ThreadingActor, BaseMixer):
    """Mixer which just stores and reports the chosen volume."""

    def __init__(self):
        super(DummyMixer, self).__init__()
        self._volume = None

    def get_volume(self):
        return self._volume

    def set_volume(self, volume):
        self._volume = volume

import logging

from pykka.actor import ThreadingActor

from mopidy import settings
from mopidy.mixers.base import BaseMixer

logger = logging.getLogger(u'mopidy.mixers.denon')

class DenonMixer(ThreadingActor, BaseMixer):
    """
    Mixer for controlling Denon amplifiers and receivers using the RS-232
    protocol.

    The external mixer is the authoritative source for the current volume.
    This allows the user to use his remote control the volume without Mopidy
    cancelling the volume setting.

    **Dependencies**

    - pyserial (python-serial on Debian/Ubuntu)

    **Settings**

    - :attr:`mopidy.settings.MIXER_EXT_PORT` -- Example: ``/dev/ttyUSB0``
    """

from subprocess import Popen, PIPE
import time

from pykka.actor import ThreadingActor

from mopidy.mixers.base import BaseMixer

class OsaMixer(ThreadingActor, BaseMixer):
    """
    Mixer which uses ``osascript`` on OS X to control volume.

    **Dependencies:**

    - None

    **Settings:**

    - None
    """

    CACHE_TTL = 30

    _cache = None
    _last_update = None

from pykka.actor import ThreadingActor

from mopidy.outputs.base import BaseOutput

class DummyOutput(ThreadingActor, BaseOutput):
    """
    Audio output used for testing.
    """

    # pylint: disable = R0902
    # Too many instance attributes (9/7)

    #: For testing. Contains the last URI passed to :meth:`play_uri`.
    uri = None

    #: For testing. Contains the last capabilities passed to
    #: :meth:`deliver_data`.
    capabilities = None

    #: For testing. Contains the last data passed to :meth:`deliver_data`.
    data = None

import alsaaudio
import logging

from pykka.actor import ThreadingActor

from mopidy import settings
from mopidy.mixers.base import BaseMixer

logger = logging.getLogger('mopidy.mixers.alsa')

class AlsaMixer(ThreadingActor, BaseMixer):
    """
    Mixer which uses the Advanced Linux Sound Architecture (ALSA) to control
    volume.

    **Dependencies:**

    - pyalsaaudio >= 0.2 (python-alsaaudio on Debian/Ubuntu)

    **Settings:**

    - :attr:`mopidy.settings.MIXER_ALSA_CONTROL`
    """

    def __init__(self):
        super(AlsaMixer, self).__init__()
        self._mixer = None