How to use the xlwings.main.App function in xlwings

"""
        wb, from_xl, hwnd = None, None, None
        for arg in sys.argv:
            if arg.startswith('--wb='):
                wb = arg.split('=')[1].strip()
            elif arg.startswith('--from_xl'):
                from_xl = arg.split('=')[1].strip()
            elif arg.startswith('--hwnd'):
                hwnd = arg.split('=')[1].strip()
        if hasattr(Book, '_mock_caller'):
            # Use mocking Book, see Book.set_mock_caller()
            return cls(impl=Book._mock_caller.impl)
        elif from_xl == '1':
            fullname = wb.lower()
            if sys.platform.startswith('win'):
                app = App(impl=xlplatform.App(xl=int(hwnd)))
                if not PY3 and isinstance(fullname, str):
                    fullname = fullname.decode('mbcs')
                return cls(impl=app.books.open(fullname).impl)
            else:
                # On Mac, the same file open in two instances is not supported
                if PY3 and apps.active.version < 15:
                    fullname = fullname.encode('utf-8', 'surrogateescape').decode('mac_latin2')
                elif not PY3 and isinstance(fullname, str):
                    if apps.active.version < 15:
                        fullname = fullname.decode('mac_latin2')
                    else:
                        fullname = fullname.decode('utf-8')
                return cls(impl=Book(fullname).impl)
        elif xlplatform.BOOK_CALLER:
            # Called via OPTIMIZED_CONNECTION = True
            return cls(impl=xlplatform.Book(xlplatform.BOOK_CALLER))

def __eq__(self, other):
        return type(other) is App and other.pid == self.pid

add_to_mru=None, local=None, corrupt_load=None, impl=None):
        if not impl:
            if fullname:
                fullname = utils.fspath(fullname)
                fullname = fullname.lower()

                candidates = []
                for app in apps:
                    for wb in app.books:
                        if wb.fullname.lower() == fullname or wb.name.lower() == fullname:
                            candidates.append((app, wb))

                app = apps.active
                if len(candidates) == 0:
                    if not app:
                        app = App(add_book=False)
                    impl = app.books.open(fullname, update_links, read_only, format, password, write_res_password,
                                          ignore_read_only_recommended, origin, delimiter, editable, notify, converter,
                                          add_to_mru, local, corrupt_load).impl
                elif len(candidates) > 1:
                    raise Exception("Workbook '%s' is open in more than one Excel instance." % fullname)
                else:
                    impl = candidates[0][1].impl
            else:
                # Open Excel if necessary and create a new workbook
                if apps.active:
                    impl = apps.active.books.add().impl
                else:
                    app = App()
                    impl = app.books[0].impl

        self.impl = impl

if len(candidates) == 0:
                    if not app:
                        app = App(add_book=False)
                    impl = app.books.open(fullname, update_links, read_only, format, password, write_res_password,
                                          ignore_read_only_recommended, origin, delimiter, editable, notify, converter,
                                          add_to_mru, local, corrupt_load).impl
                elif len(candidates) > 1:
                    raise Exception("Workbook '%s' is open in more than one Excel instance." % fullname)
                else:
                    impl = candidates[0][1].impl
            else:
                # Open Excel if necessary and create a new workbook
                if apps.active:
                    impl = apps.active.books.add().impl
                else:
                    app = App()
                    impl = app.books[0].impl

        self.impl = impl

def app(self):
        """
        Returns an app object that represents the creator of the book.

        .. versionadded:: 0.9.0
        """
        return App(impl=self.impl.app)

def add(self):
        """
        Creates a new App. The new App becomes the active one. Returns an App object.
        """
        return App()

def __iter__(self):
        for app in self.impl:
            yield App(impl=app)

def __getitem__(self, item):
        return App(impl=self.impl[item])

def active(self):
        """
        Returns the active app.

        .. versionadded:: 0.9.0
        """
        for app in self.impl:
            return App(impl=app)
        return None