How to save a JSON file using flet in Python

Question

I have a script which creates JSON and save it in the current directory where the python script is lying. I want a GUI interface where I can save that output JSON in a particular folder selected form the Flet interface.

import flet
from flet import (
    ElevatedButton,
    FilePicker,
    FilePickerResultEvent,
    Page,
    Row,
    Text,
    icons,
)


def main(page: Page):
    page.bgcolor = "white"
    # Pick files dialog
    def pick_files_result(e: FilePickerResultEvent):
        selected_files.value = (
            ", ".join(map(lambda f: f.name, e.files)) if e.files else "Cancelled!"
        )
        selected_files.update()

    pick_files_dialog = FilePicker(on_result=pick_files_result)
    selected_files = Text()

    # Save file dialog
    def save_file_result(e: FilePickerResultEvent):
        save_file_path.value = e.path if e.path else "Cancelled!"
        save_file_path.update()

    save_file_dialog = FilePicker(on_result=save_file_result)
    save_file_path = Text()

    # hide all dialogs in overlay
    page.overlay.extend([pick_files_dialog, save_file_dialog])

    page.add(
        Row(
            [
                ElevatedButton(
                    "Pick files",
                    icon=icons.UPLOAD_FILE,
                    on_click=lambda _: pick_files_dialog.pick_files(
                        allow_multiple=True
                    ),
                ),
                selected_files,
            ]
        ),
        Row(
            [
                ElevatedButton(
                    "Save file",
                    icon=icons.SAVE,
                    on_click=lambda _: save_file_dialog.save_file(),
                    disabled=page.web,
                ),
                save_file_path,
            ]
        ),
    )

flet.app(target=main)

This is the program which I took from the flet documentation but cant understand how can I store the output json from the above code