How to use the blinker.Signal function in blinker

def __init__(self, prompt='', on_change=None, on_move=None, on_accept=None, on_cancel=None,
                 on_complete_next=None, on_complete_prev=None, completer=None,
                 history_file=None, history_size=1000, **kwargs):
        # Widgets
        self._editw = urwid.Edit(prompt, wrap='clip')
        self._candsw = CompletionCandidatesWidget(completer)
        self._groupw = Group(cls=urwid.Pile)
        self._groupw.add(name='candidates', widget=self._candsw, visible=False, options=10)
        self._groupw.add(name='cmdline', widget=self._editw, visible=True, options='pack')
        super().__init__(self._groupw)

        # Callbacks
        self._on_change = blinker.Signal()
        self._on_move = blinker.Signal()
        self._on_accept = blinker.Signal()
        self._on_cancel = blinker.Signal()
        self._on_complete_next = blinker.Signal()
        self._on_complete_prev = blinker.Signal()

        # Completion
        self._completer = completer
        self._on_complete_next.connect(self._cb_complete_next)
        self._on_complete_prev.connect(self._cb_complete_prev)
        self._on_change.connect(self._cb_change)
        self._on_move.connect(self._cb_move)
        self._user_input = None

        # History
        self._history = []
        self._history_size = history_size
        self._history_pos = -1

def __init__(self, app):

        self.transactionPushed = Signal(object)

        self.app = app
        self.currentIndex = 0
        self.stack = OrderedDict()
        self.transaction = None

def __init__(self, name, parent, direction, **kwargs):
        super(AnyPin, self).__init__(name, parent, direction, **kwargs)
        self.typeChanged = Signal(str)
        self.dataTypeBeenSet = Signal()
        self.setDefaultValue(None)
        self._isAny = True
        # if True, setType and setDefault will work only once
        self.singleInit = False
        self.enableOptions(PinOptions.ChangeTypeOnConnection)
        self._defaultSupportedDataTypes = self._supportedDataTypes = tuple([pin.__name__ for pin in getAllPinClasses() if pin.IsValuePin()])
        self.canChange = True
        self.super = None

import blinker

focus = blinker.Signal()
set_prompt = blinker.Signal()
set_prompt_yn = blinker.Signal()
set_message = blinker.Signal()
redraw_status = blinker.Signal()
call_delay = blinker.Signal()

self._state = ReportState(run_on_save=False, report_is_running=False)

        # TODO: Add signal that file changed. Then subscribe to it from
        # server.py

        # TODO: Move to scriptrunner.py
        self.state_changed = Signal(
            doc="""Emitted when our state changes

            Parameters
            ----------
            state : ReportState
                the ReportSession's current ReportState
            """)

        self.on_report_changed = Signal(
            doc="""Emitted when our report's source_file is changed on disk,
            and self.run_on_save is False. When this happens, the browser
            alerts the user that the report has changed and prompts them to
            re-run it.
            """
        )

        self.on_report_was_manually_stopped = Signal(
            doc="""Emitted when our running report is manually stopped."""
        )

        self.set_client_connection(initial_client_connection)

def on_error(self):
        """Emitted when an error is received.

        The signal sender is the consumer and the ``error`` is sent as an
        argument.
        """
        return blinker.Signal(doc='Emitted when a error is received.')

def __init__(self):
        self.deferred: typing.Dict[str, str] = {}
        self.changed = blinker.Signal()
        self.errored = blinker.Signal()
        # Options must be the last attribute here - after that, we raise an
        # error for attribute assigment to unknown options.
        self._options: typing.Dict[str, typing.Any] = {}

import urwid
import blinker
import textwrap
from mitmproxy.tools.console import layoutwidget
from mitmproxy.tools.console import signals

HELP_HEIGHT = 5

command_focus_change = blinker.Signal()


class CommandItem(urwid.WidgetWrap):
    def __init__(self, walker, cmd, focused):
        self.walker, self.cmd, self.focused = walker, cmd, focused
        super().__init__(None)
        self._w = self.get_widget()

    def get_widget(self):
        parts = [
            ("focus", ">> " if self.focused else "   "),
            ("text", "async " if self.cmd.asyncf else "      "),
            ("title", self.cmd.path),
            ("text", " "),
            ("text", " ".join(self.cmd.paramnames())),
        ]

Parameters
            ----------
            state : ReportState
                the ReportSession's current ReportState
            """)

        self.on_report_changed = Signal(
            doc="""Emitted when our report's source_file is changed on disk,
            and self.run_on_save is False. When this happens, the browser
            alerts the user that the report has changed and prompts them to
            re-run it.
            """
        )

        self.on_report_was_manually_stopped = Signal(
            doc="""Emitted when our running report is manually stopped."""
        )

        self.set_client_connection(initial_client_connection)