How to use the hotdoc.utils.signals.Signal function in hotdoc

if not line:
                        return None
                    res.append(line)
            return ''.join(res), lang

        with io.open(include_path, 'r', encoding='utf-8') as _:
            return _.read(), lang


# pylint: disable=too-many-instance-attributes
class Project(object):
    """
    Banana banana
    """

    formatted_signal = Signal()

    def __init__(self):
        self.output = None
        self.tree = None
        self.change_tracker = None
        self.output_format = None
        self.include_paths = None
        self.extensions = {}
        self.tag_validators = {}
        self.link_resolver = None
        self.incremental = False
        self.database = None
        self.config = None
        self.project_name = None
        self.project_version = None
        self.sitemap_path = None

self.app = app

        if self.app.incremental:
            self.__all_pages = self.__load_private(
                'pages-%s.p' % self.project.sanitized_name)
        else:
            self.__all_pages = {}

        self.__placeholders = {}
        self.root = None
        self.__dep_map = project.dependency_map
        self.__fill_dep_map()

        cmark.hotdoc_to_ast(u'', self)
        self.__extensions = {}
        self.resolve_placeholder_signal = Signal(optimized=True)
        self.list_override_pages_signal = Signal(optimized=True)
        self.update_signal = Signal()
        self.resolving_symbol_signal = Signal()

def __init__(self, private_folder):
        self.comment_added_signal = Signal()

        self.__comments = OrderedDict()
        self.__symbols = OrderedDict()
        self.__aliased = defaultdict(list)
        self.__aliases = OrderedDict()
        self.__private_folder = private_folder or '/tmp'

from hotdoc.utils.signals import Signal


def dict_to_html_attrs(dict_):
    """
    Banana banana
    """
    res = ' '.join('%s="%s"' % (k, v) for k, v in dict_.items())
    return res


class Link:
    """
    Banana banana
    """
    resolving_title_signal = Signal()

    def __init__(self, ref, title, id_, mandatory=False):
        self.ref = None
        self._title = None
        # Whether the link should be always resolved when true and a warning
        # otherwise
        self.__mandatory = mandatory
        # Ensure we warn only once for a unresolved mandatory link
        self.__warned = False

        if title:
            self._title = str(title)
        if ref:
            self.ref = str(ref)

        self.id_ = id_

def __init__(self, database):
        self.__links = {}
        self.__doc_db = database
        self.get_link_signal = Signal()
        self.resolving_link_signal = Signal(optimized=True)

self._ordering = [InterfaceSymbol, ClassSymbol, ConstructorSymbol,
                          MethodSymbol, ClassMethodSymbol, FunctionSymbol,
                          FunctionMacroSymbol, SignalSymbol, PropertySymbol,
                          StructSymbol, VFunctionSymbol, EnumSymbol,
                          ConstantSymbol, ExportedVariableSymbol, AliasSymbol,
                          CallbackSymbol]

        self._docstring_formatter = self._make_docstring_formatter()
        self._current_page = None
        self.extra_assets = None
        self.add_anchors = False
        self.number_headings = False
        self.writing_page_signal = Signal()
        self.formatting_page_signal = Signal()
        self.formatting_symbol_signal = Signal()
        self._order_by_parent = False

        self.__cache_dir = os.path.join(self.extension.app.private_folder,
                                        'cache')
        self.__page_transform = etree.XSLT(XSLT_PAGE_TRANSFORM)

def test_connect_func(self):
        """Banana Banana"""
        called = []

        def func(arg, extra_arg):
            """Banana Banana"""
            self.assertEqual(arg, 1)
            self.assertEqual(extra_arg, "extra")
            called.append(True)

        signal = Signal()
        signal.connect(func, "extra")

        signal(1)
        self.assertEqual(called, [True])

self.extra_asset_folders = OrderedSet()
        self.extra_assets = {}

        if dependency_map is None:
            self.dependency_map = {}
        else:
            self.dependency_map = dependency_map

        if os.name == 'nt':
            self.datadir = os.path.join(
                os.path.dirname(__file__), '..', 'share')
        else:
            self.datadir = "/usr/share"

        self.formatted_signal = Signal()
        self.written_out_signal = Signal()

        self.is_toplevel = False

self.__all_pages = self.__load_private(
                'pages-%s.p' % self.project.sanitized_name)
        else:
            self.__all_pages = {}

        self.__placeholders = {}
        self.root = None
        self.__dep_map = project.dependency_map
        self.__fill_dep_map()

        cmark.hotdoc_to_ast(u'', self)
        self.__extensions = {}
        self.resolve_placeholder_signal = Signal(optimized=True)
        self.list_override_pages_signal = Signal(optimized=True)
        self.update_signal = Signal()
        self.resolving_symbol_signal = Signal()

self.subprojects = {}
        self.extra_asset_folders = OrderedSet()
        self.extra_assets = {}

        if dependency_map is None:
            self.dependency_map = {}
        else:
            self.dependency_map = dependency_map

        if os.name == 'nt':
            self.datadir = os.path.join(
                os.path.dirname(__file__), '..', 'share')
        else:
            self.datadir = "/usr/share"

        self.formatted_signal = Signal()
        self.written_out_signal = Signal()

        self.is_toplevel = False