How to use the gaphor.core.gettext function in gaphor

def load(self, filename):
        """Load the Gaphor model from the supplied file name.  A status window
        displays the loading progress.  The load generator updates the progress
        queue.  The loader is passed to a GIdleThread which executes the load
        generator.  If loading is successful, the filename is set."""

        queue = Queue()
        status_window: Optional[StatusWindow]
        main_window = self.main_window
        status_window = StatusWindow(
            gettext("Loading..."),
            gettext("Loading model from {filename}").format(filename=filename),
            parent=main_window.window,
            queue=queue,
        )

        try:
            loader = storage.load_generator(
                filename.encode("utf-8"), self.element_factory
            )
            worker = GIdleThread(loader, queue)

            worker.start()
            worker.wait()

            if worker.error:
                worker.reraise()

"""Save the current UML model to the specified file name.  Before
        writing the model file, this will verify that there are no orphan
        references.  It will also verify that the filename has the correct
        extension.  A status window is displayed while the GIdleThread
        is executed.  This thread actually saves the model."""

        if not filename or not len(filename):
            return

        self.verify_orphans()
        filename = self.verify_filename(filename)

        main_window = self.main_window
        queue = Queue()
        status_window = StatusWindow(
            gettext("Saving..."),
            gettext("Saving model to {filename}").format(filename=filename),
            parent=main_window.window,
            queue=queue,
        )
        try:
            with open(filename.encode("utf-8"), "w") as out:
                saver = storage.save_generator(XMLWriter(out), self.element_factory)
                worker = GIdleThread(saver, queue)
                worker.start()
                worker.wait()

            if worker.error:
                worker.reraise()

            self.filename = filename
            self.event_manager.handle(FileSaved(self, filename))

ToolDef(
                "toolbox-interaction",
                gettext("Interaction"),
                "gaphor-interaction-symbolic",
                "N",
                item_factory=PlacementTool.new_item_factory(
                    diagram.interactions.InteractionItem,
                    UML.Interaction,
                    config_func=namespace_config,
                ),
                handle_index=SE,
            ),
        ),
    ),
    (
        gettext("States"),
        (
            ToolDef(
                "toolbox-state",
                gettext("State"),
                "gaphor-state-symbolic",
                "s",
                item_factory=PlacementTool.new_item_factory(
                    diagram.states.StateItem, UML.State, config_func=namespace_config
                ),
                handle_index=SE,
            ),
            ToolDef(
                "toolbox-initial-pseudostate",
                gettext("Initial Pseudostate"),
                "gaphor-initial-pseudostate-symbolic",
                "S",

),
            ToolDef(
                "toolbox-implementation",
                gettext("Implementation"),
                "gaphor-implementation-symbolic",
                "I",
                PlacementTool.new_item_factory(diagram.classes.ImplementationItem),
            ),
        ),
    ),
    (
        gettext("Components"),
        (
            ToolDef(
                "toolbox-component",
                gettext("Component"),
                "gaphor-component-symbolic",
                "o",
                PlacementTool.new_item_factory(
                    diagram.components.ComponentItem,
                    UML.Component,
                    config_func=namespace_config,
                ),
                handle_index=SE,
            ),
            ToolDef(
                "toolbox-artifact",
                gettext("Artifact"),
                "gaphor-artifact-symbolic",
                "h",
                PlacementTool.new_item_factory(
                    diagram.components.ArtifactItem,

),
            ToolDef(
                "toolbox-comment-line",
                gettext("Comment line"),
                "gaphor-comment-line-symbolic",
                "K",
                PlacementTool.new_item_factory(diagram.general.CommentLineItem),
            ),
        ),
    ),
    (
        gettext("Classes"),
        (
            ToolDef(
                "toolbox-class",
                gettext("Class"),
                "gaphor-class-symbolic",
                "c",
                item_factory=PlacementTool.new_item_factory(
                    diagram.classes.ClassItem, UML.Class, config_func=namespace_config
                ),
                handle_index=SE,
            ),
            ToolDef(
                "toolbox-interface",
                gettext("Interface"),
                "gaphor-interface-symbolic",
                "i",
                item_factory=PlacementTool.new_item_factory(
                    diagram.classes.InterfaceItem,
                    UML.Interface,
                    config_func=namespace_config,

        label=gettext("_Undo"),
        icon_name="edit-undo",
        shortcut="z",
    )
    def undo_transaction(self):
        if not self._undo_stack:
            return

        if self._current_transaction:
            logger.warning("Trying to undo a transaction, while in a transaction")
            self.commit_transaction()
        transaction = self._undo_stack.pop()

        # Store stacks
        undo_stack = list(self._undo_stack)
        redo_stack = list(self._redo_stack)
        self._undo_stack = []

def create_hamburger_model(export_menu, tools_menu):
    model = Gio.Menu.new()

    part = Gio.Menu.new()
    part.append(gettext("New"), "win.file-new")
    part.append(gettext("New from Template"), "win.file-new-template")
    model.append_section(None, part)

    part = Gio.Menu.new()
    part.append(gettext("Save As..."), "win.file-save-as")
    part.append_submenu(gettext("Export"), export_menu)
    model.append_section(None, part)

    part = Gio.Menu.new()
    part.append_submenu(gettext("Tools"), tools_menu)
    model.append_section(None, part)

    part = Gio.Menu.new()
    part.append(gettext("Preferences"), "app.preferences")
    part.append(gettext("Keyboard Shortcuts"), "app.shortcuts")
    part.append(gettext("About Gaphor"), "app.about")

),
                handle_index=SE,
            ),
            ToolDef(
                "toolbox-activity-final-node",
                gettext("Activity final node"),
                "gaphor-activity-final-node-symbolic",
                "f",
                item_factory=PlacementTool.new_item_factory(
                    diagram.actions.ActivityFinalNodeItem, UML.ActivityFinalNode
                ),
                handle_index=SE,
            ),
            ToolDef(
                "toolbox-flow-final-node",
                gettext("Flow final node"),
                "gaphor-flow-final-node-symbolic",
                "w",
                item_factory=PlacementTool.new_item_factory(
                    diagram.actions.FlowFinalNodeItem, UML.FlowFinalNode
                ),
                handle_index=SE,
            ),
            ToolDef(
                "toolbox-decision-node",
                gettext("Decision/merge node"),
                "gaphor-decision-node-symbolic",
                "g",
                item_factory=PlacementTool.new_item_factory(
                    diagram.actions.DecisionNodeItem, UML.DecisionNode
                ),
                handle_index=SE,

(
            ToolDef(
                "toolbox-lifeline",
                gettext("Lifeline"),
                "gaphor-lifeline-symbolic",
                "v",
                item_factory=PlacementTool.new_item_factory(
                    diagram.interactions.LifelineItem,
                    UML.Lifeline,
                    config_func=namespace_config,
                ),
                handle_index=SE,
            ),
            ToolDef(
                "toolbox-message",
                gettext("Message"),
                "gaphor-message-symbolic",
                "M",
                item_factory=PlacementTool.new_item_factory(
                    diagram.interactions.MessageItem
                ),
            ),
            ToolDef(
                "toolbox-interaction",
                gettext("Interaction"),
                "gaphor-interaction-symbolic",
                "N",
                item_factory=PlacementTool.new_item_factory(
                    diagram.interactions.InteractionItem,
                    UML.Interaction,
                    config_func=namespace_config,
                ),

def action_new_from_template(self):
        """This menu action opens the new model from template dialog."""

        filters = [
            {"name": gettext("Gaphor Models"), "pattern": "*.gaphor"},
            {"name": gettext("All Files"), "pattern": "*"},
        ]

        file_dialog = FileDialog(
            gettext("New Gaphor Model From Template"), filters=filters
        )

        filename = file_dialog.selection

        file_dialog.destroy()

        log.debug(filename)

        if filename:
            self.load(filename)
            self.filename = None