How to use the hangups.pblite.Message function in hangups

(None, Field(is_optional=True)),  # always None?
    (None, Field(is_optional=True)),  # always 0? (expiration_timestamp?)
    ('chat_message', CLIENT_CHAT_MESSAGE),
    (None, Field(is_optional=True)),  # always None?
    ('membership_change', CLIENT_MEMBERSHIP_CHANGE),
    ('conversation_rename', CLIENT_CONVERSATION_RENAME),
    ('hangout_event', CLIENT_HANGOUT_EVENT),
    ('event_id', Field(is_optional=True)),
    ('advances_sort_timestamp', Field(is_optional=True)),
    ('otr_modification', CLIENT_OTR_MODIFICATION),
    (None, Field(is_optional=True)),  # 0, 1 or None? related to notifications?
    ('event_otr', EnumField(OffTheRecordStatus)),
    (None, Field()),  # always 1? (advances_sort_timestamp?)
)

CLIENT_EVENT_NOTIFICATION = Message(
    ('event', CLIENT_EVENT),
    is_optional=True,
)

CLIENT_WATERMARK_NOTIFICATION = Message(
    ('participant_id', USER_ID),
    ('conversation_id', CONVERSATION_ID),
    ('latest_read_timestamp', Field()),
    is_optional=True,
)

CLIENT_STATE_UPDATE_HEADER = Message(
    ('active_client_state', EnumField(ActiveClientState)),
    (None, Field(is_optional=True)),
    ('request_trace_id', Field()),
    (None, Field(is_optional=True)),

CLIENT_RESPONSE_HEADER = Message(
    ('status', Field()),  # 1 => success
    (None, Field(is_optional=True)),
    (None, Field(is_optional=True)),
    ('request_trace_id', Field()),
    ('current_server_time', Field()),
)

CLIENT_SYNC_ALL_NEW_EVENTS_RESPONSE = Message(
    (None, Field()),  # 'csanerp'
    ('response_header', CLIENT_RESPONSE_HEADER),
    ('sync_timestamp', Field()),
    ('conversation_state', RepeatedField(CLIENT_CONVERSATION_STATE)),
)

CLIENT_GET_CONVERSATION_RESPONSE = Message(
    (None, Field()),  # 'cgcrp'
    ('response_header', CLIENT_RESPONSE_HEADER),
    ('conversation_state', CLIENT_CONVERSATION_STATE),
)

CLIENT_GET_ENTITY_BY_ID_RESPONSE = Message(
    (None, Field()),  # 'cgebirp'
    ('response_header', CLIENT_RESPONSE_HEADER),
    ('entities', RepeatedField(CLIENT_ENTITY)),
)

(None, Field()),  # always 1? (advances_sort_timestamp?)
)

CLIENT_EVENT_NOTIFICATION = Message(
    ('event', CLIENT_EVENT),
    is_optional=True,
)

CLIENT_WATERMARK_NOTIFICATION = Message(
    ('participant_id', USER_ID),
    ('conversation_id', CONVERSATION_ID),
    ('latest_read_timestamp', Field()),
    is_optional=True,
)

CLIENT_STATE_UPDATE_HEADER = Message(
    ('active_client_state', EnumField(ActiveClientState)),
    (None, Field(is_optional=True)),
    ('request_trace_id', Field()),
    (None, Field(is_optional=True)),
    ('current_server_time', Field()),
    (None, Field(is_optional=True)),
    (None, Field(is_optional=True)),
    # optional ID of the client causing the update?
    (None, Field(is_optional=True)),
)

CLIENT_STATE_UPDATE = Message(
    ('state_update_header', CLIENT_STATE_UPDATE_HEADER),
    ('conversation_notification', Field(is_optional=True)),  # always None?
    ('event_notification', CLIENT_EVENT_NOTIFICATION),
    ('focus_notification', CLIENT_SET_FOCUS_NOTIFICATION),

('type_', RepeatedField(Field())),
        ('data', Field()),  # can be a dict
    )),
)

CLIENT_CHAT_MESSAGE = Message(
    (None, Field(is_optional=True)),  # always None?
    ('annotation', RepeatedField(Field(), is_optional=True)),
    ('message_content', Message(
        ('segment', RepeatedField(MESSAGE_SEGMENT, is_optional=True)),
        ('attachment', RepeatedField(MESSAGE_ATTACHMENT, is_optional=True)),
    )),
    is_optional=True,
)

CLIENT_CONVERSATION_RENAME = Message(
    ('new_name', Field()),
    ('old_name', Field()),
    is_optional=True,
)

CLIENT_HANGOUT_EVENT = Message(
    ('event_type', EnumField(ClientHangoutEventType)),
    ('participant_id', RepeatedField(USER_ID)),
    ('hangout_duration_secs', Field(is_optional=True)),
    ('transferred_conversation_id', Field(is_optional=True)),  # always None?
    ('refresh_timeout_secs', Field(is_optional=True)),
    ('is_periodic_refresh', Field(is_optional=True)),
    (None, Field(is_optional=True)),  # always 1?
    is_optional=True,
)

('old_name', Field()),
    is_optional=True,
)

CLIENT_HANGOUT_EVENT = Message(
    ('event_type', EnumField(ClientHangoutEventType)),
    ('participant_id', RepeatedField(USER_ID)),
    ('hangout_duration_secs', Field(is_optional=True)),
    ('transferred_conversation_id', Field(is_optional=True)),  # always None?
    ('refresh_timeout_secs', Field(is_optional=True)),
    ('is_periodic_refresh', Field(is_optional=True)),
    (None, Field(is_optional=True)),  # always 1?
    is_optional=True,
)

CLIENT_OTR_MODIFICATION = Message(
    ('old_otr_status', EnumField(OffTheRecordStatus)),
    ('new_otr_status', EnumField(OffTheRecordStatus)),
    ('old_otr_toggle', EnumField(ClientOffTheRecordToggle)),
    ('new_otr_toggle', EnumField(ClientOffTheRecordToggle)),
    is_optional=True,
)

CLIENT_MEMBERSHIP_CHANGE = Message(
    ('type_', EnumField(MembershipChangeType)),
    (None, RepeatedField(Field())),
    ('participant_ids', RepeatedField(USER_ID)),
    (None, Field()),
    is_optional=True,
)

CLIENT_EVENT = Message(

(None, Field(is_optional=True)),  # always None?
    ('group1', ENTITY_GROUP),
    ('group2', ENTITY_GROUP),
    ('group3', ENTITY_GROUP),
    ('group4', ENTITY_GROUP),
    ('group5', ENTITY_GROUP),

)

CLIENT_GET_SELF_INFO_RESPONSE = Message(
    (None, Field()),  # 'cgsirp'
    (None, Field()),  # response header
    ('self_entity', CLIENT_ENTITY),
)

CLIENT_RESPONSE_HEADER = Message(
    ('status', Field()),  # 1 => success
    (None, Field(is_optional=True)),
    (None, Field(is_optional=True)),
    ('request_trace_id', Field()),
    ('current_server_time', Field()),
)

CLIENT_SYNC_ALL_NEW_EVENTS_RESPONSE = Message(
    (None, Field()),  # 'csanerp'
    ('response_header', CLIENT_RESPONSE_HEADER),
    ('sync_timestamp', Field()),
    ('conversation_state', RepeatedField(CLIENT_CONVERSATION_STATE)),
)

CLIENT_GET_CONVERSATION_RESPONSE = Message(
    (None, Field()),  # 'cgcrp'

('old_otr_status', EnumField(OffTheRecordStatus)),
    ('new_otr_status', EnumField(OffTheRecordStatus)),
    ('old_otr_toggle', EnumField(ClientOffTheRecordToggle)),
    ('new_otr_toggle', EnumField(ClientOffTheRecordToggle)),
    is_optional=True,
)

CLIENT_MEMBERSHIP_CHANGE = Message(
    ('type_', EnumField(MembershipChangeType)),
    (None, RepeatedField(Field())),
    ('participant_ids', RepeatedField(USER_ID)),
    (None, Field()),
    is_optional=True,
)

CLIENT_EVENT = Message(
    ('conversation_id', CONVERSATION_ID),
    ('sender_id', OPTIONAL_USER_ID),
    ('timestamp', Field()),
    ('self_event_state', Message(
        ('user_id', USER_ID),
        ('client_generated_id', Field(is_optional=True)),
        ('notification_level', EnumField(ClientNotificationLevel)),
        is_optional=True,
    )),
    (None, Field(is_optional=True)),  # always None?
    (None, Field(is_optional=True)),  # always 0? (expiration_timestamp?)
    ('chat_message', CLIENT_CHAT_MESSAGE),
    (None, Field(is_optional=True)),  # always None?
    ('membership_change', CLIENT_MEMBERSHIP_CHANGE),
    ('conversation_rename', CLIENT_CONVERSATION_RENAME),
    ('hangout_event', CLIENT_HANGOUT_EVENT),

"""Active client state."""

    NO_ACTIVE_CLIENT = 0
    IS_ACTIVE_CLIENT = 1
    OTHER_CLIENT_IS_ACTIVE = 2


##############################################################################
# pblite Messages
##############################################################################

CONVERSATION_ID = Message(
    ('id_', Field()),
)

USER_ID = Message(
    ('gaia_id', Field()),
    ('chat_id', Field()),
)

OPTIONAL_USER_ID = Message(
    ('gaia_id', Field()),
    ('chat_id', Field()),
    is_optional=True,
)

CLIENT_SET_TYPING_NOTIFICATION = Message(
    ('conversation_id', CONVERSATION_ID),
    ('user_id', USER_ID),
    ('timestamp', Field()),
    ('status', EnumField(TypingStatus)),
    is_optional=True,

class ActiveClientState(enum.Enum):

    """Active client state."""

    NO_ACTIVE_CLIENT = 0
    IS_ACTIVE_CLIENT = 1
    OTHER_CLIENT_IS_ACTIVE = 2


##############################################################################
# pblite Messages
##############################################################################

CONVERSATION_ID = Message(
    ('id_', Field()),
)

USER_ID = Message(
    ('gaia_id', Field()),
    ('chat_id', Field()),
)

OPTIONAL_USER_ID = Message(
    ('gaia_id', Field()),
    ('chat_id', Field()),
    is_optional=True,
)

CLIENT_SET_TYPING_NOTIFICATION = Message(
    ('conversation_id', CONVERSATION_ID),

('type_', EnumField(SegmentType)),
    ('text', Field(is_optional=True)),  # Can be None for linebreaks
    ('formatting', Message(
        ('bold', Field(is_optional=True)),
        ('italic', Field(is_optional=True)),
        ('strikethrough', Field(is_optional=True)),
        ('underline', Field(is_optional=True)),
        is_optional=True,
    )),
    ('link_data', Message(
        ('link_target', Field(is_optional=True)),
        is_optional=True,
    )),
)

MESSAGE_ATTACHMENT = Message(
    ('embed_item', Message(
        # 249 (PLUS_PHOTO), 340, 335, 0
        ('type_', RepeatedField(Field())),
        ('data', Field()),  # can be a dict
    )),
)

CLIENT_CHAT_MESSAGE = Message(
    (None, Field(is_optional=True)),  # always None?
    ('annotation', RepeatedField(Field(), is_optional=True)),
    ('message_content', Message(
        ('segment', RepeatedField(MESSAGE_SEGMENT, is_optional=True)),
        ('attachment', RepeatedField(MESSAGE_ATTACHMENT, is_optional=True)),
    )),
    is_optional=True,
)