How to use the wagtail.wagtailadmin.edit_handlers.FieldPanel function in wagtail

'related_links',
    ) + ContactFieldsMixin.api_fields

    search_fields = Page.search_fields + (
        index.SearchField('first_name'),
        index.SearchField('last_name'),
        index.SearchField('intro'),
        index.SearchField('biography'),
    )

class PersonPageRelatedLink(Orderable, AbstractRelatedLink):
    page = ParentalKey('PersonPage', related_name='related_links')

PersonPage.content_panels = Page.content_panels + [
    FieldPanel('first_name'),
    FieldPanel('last_name'),
    FieldPanel('intro', classname="full"),
    FieldPanel('biography', classname="full"),
    ImageChooserPanel('image'),
    MultiFieldPanel(ContactFieldsMixin.panels, "Contact"),
    InlinePanel(PersonPage, 'related_links', label="Related links"),
]

PersonPage.promote_panels = [
    MultiFieldPanel(Page.promote_panels, "Common page configuration"),
    ImageChooserPanel('feed_image'),
]


# Contact page

class ContactPage(Page, ContactFieldsMixin):

@python_2_unicode_compatible
class Advert(models.Model):
    page = models.ForeignKey(
        'wagtailcore.Page',
        related_name='adverts',
        null=True,
        blank=True
    )
    url = models.URLField(null=True, blank=True)
    text = models.CharField(max_length=255)

    panels = [
        PageChooserPanel('page'),
        FieldPanel('url'),
        FieldPanel('text'),
    ]

    api_fields = ['page', 'url', 'text']

    def __str__(self):
        return self.text

register_snippet(Advert)


# Home Page

class HomePageCarouselItem(Orderable, CarouselItem):
    page = ParentalKey('demo.HomePage', related_name='carousel_items')

message = 'Could not export event\n\nUnrecognised format: ' + request.GET['format']
                return HttpResponse(message, content_type='text/plain')
        else:
            # Display event page as usual
            return super(EventPage, self).serve(request)

EventPage.content_panels = [
    FieldPanel('title', classname="full title"),
    FieldPanel('date_from'),
    FieldPanel('date_to'),
    FieldPanel('time_from'),
    FieldPanel('time_to'),
    FieldPanel('location'),
    FieldPanel('audience'),
    FieldPanel('cost'),
    FieldPanel('signup_link'),
    InlinePanel(EventPage, 'carousel_items', label="Carousel items"),
    FieldPanel('body', classname="full"),
    InlinePanel(EventPage, 'speakers', label="Speakers"),
    InlinePanel(EventPage, 'related_links', label="Related links"),
]

EventPage.promote_panels = Page.promote_panels + [
    ImageChooserPanel('feed_image'),
]


class FormField(AbstractFormField):
    page = ParentalKey('FormPage', related_name='form_fields')

class FormPage(AbstractEmailForm):
    intro = RichTextField(blank=True)

analytics = models.CharField(max_length=60, default="", blank=True,
        help_text="Optional web analytics property code")

    contact_form = models.ForeignKey(
        'home.ContactForm',
        null=True, blank=True,
        on_delete=models.SET_NULL,
        related_name='+',
    )

    panels = Page.content_panels + [
        FieldPanel('title_fr'),
        FieldPanel('address'),
        FieldPanel('phone'),
        FieldPanel('email'),
        FieldPanel('www'),
        FieldPanel('map_url'),
        FieldPanel('analytics'),
        PageChooserPanel('contact_form', 'home.ContactForm'),
    ]

    def phone_link(self):
        return 'tel:%s' % self.phone.replace(' ', '')
    def email_link(self):
        return 'mailto:%s' % self.email
    def www_domain(self):
        return self.www.replace('http://', '').replace('https://', '')
    def is_google_analytics(self):
        return self.analytics.startswith('UA-')
    def get_piwik_analytics(self):
        # When formatted as "server|site_id", assume Piwik
        if not '|' in self.analytics: return False

]

    edit_handler = TabbedInterface([
        ObjectList(general_panels, heading='General'),
        ObjectList(content_panels, heading='Content'),
        ObjectList(adhocracy_panel, heading='Adhocracy')

    ])


class FlashpollProjectPage(ProjectPage):

    embedurl = models.URLField()

    flashpoll_panel = [
        FieldPanel('embedurl')
    ]

    general_panels = [
        FieldPanel('title', classname='title'),
        FieldPanel('slug'),
        ImageChooserPanel('image'),
        FieldPanel('projecttype'),
        FieldPanel('organisation')
    ]

    content_panels = [
        MultiFieldPanel(
            [
                FieldPanel('title_en'),
                FieldPanel('teaser_en'),
            ]

)
    )

    promote_panels = [
        MultiFieldPanel([
            FieldPanel('seo_title'),
            FieldPanel('slug'),
        ], "Common page configuration"),

        MultiFieldPanel([
            ImageChooserPanel('social_image'),
            FieldPanel('search_description'),
        ], "Social networks"),

        MultiFieldPanel([
            FieldPanel('show_in_menus'),
        ], "Cross-page behavior"),
    ]

    class Meta:
        abstract = True

the next scheduled event date.

        :rtype: datetime.date.
        """
        date = self.date
        if date is None:
            date = Event.objects.get_next_occurence(self.event)
        return date

BaseEventPage.content_panels = [
    FieldPanel('title', classname='full title'),
    EventChooserPanel('event'),
    MultiFieldPanel([
        FieldRowPanel([
            FieldPanel('date', classname='col12'),
            FieldPanel('start', classname='col6'),
            FieldPanel('end', classname='col6'),
        ], classname='label-above'),
    ], _(u'Event Details'), classname='publishing'),
]

]


class FormField(AbstractFormField):
    page = ParentalKey('FormPage', related_name='form_fields')


class FormPage(AbstractEmailForm):
    intro = RichTextField(blank=True)
    thank_you_text = RichTextField(blank=True)

FormPage.content_panels = [
    FieldPanel('title', classname="full title"),
    FieldPanel('intro', classname="full"),
    InlinePanel('form_fields', label="Form fields"),
    FieldPanel('thank_you_text', classname="full"),
    MultiFieldPanel([
        FieldPanel('to_address', classname="full"),
        FieldPanel('from_address', classname="full"),
        FieldPanel('subject', classname="full"),
    ], "Email")
]

class ArticleIndexPage(Page):
    title_fr = models.CharField(max_length=255, default="")
    trans_title = TranslatedField(
        'title',
        'title_fr',
    )

    intro_de = RichTextField(default='', blank=True)
    intro_fr = RichTextField(default='', blank=True)
    trans_intro = TranslatedField(
        'intro_de',
        'intro_fr',
    )

    content_panels = Page.content_panels + [
        FieldPanel('intro_de'),
        FieldPanel('title_fr'),
        FieldPanel('intro_fr'),
    ]

    def get_context(self, request):
        context = super(ArticleIndexPage, self).get_context(request)
        articles = ArticlePage.objects.child_of(self).live()
        context['articles'] = articles
        return context

    subpage_types = ['home.ArticlePage', 'home.ArticleIndexPage']
    class Meta:
        verbose_name = "Rubrik"

class ArticlePage(Page):
    title_fr = models.CharField(max_length=255, default="")

)
                response['Content-Disposition'] = 'attachment; filename=' + self.slug + '.ics'
                return response
            else:
                # Unrecognised format error
                message = 'Could not export event\n\nUnrecognised format: ' + request.GET['format']
                return HttpResponse(message, content_type='text/plain')
        else:
            # Display event page as usual
            return super(EventPage, self).serve(request)

EventPage.content_panels = [
    FieldPanel('title', classname="full title"),
    FieldPanel('date_from'),
    FieldPanel('date_to'),
    FieldPanel('time_from'),
    FieldPanel('time_to'),
    FieldPanel('location'),
    FieldPanel('audience'),
    FieldPanel('cost'),
    FieldPanel('signup_link'),
    InlinePanel('carousel_items', label="Carousel items"),
    FieldPanel('body', classname="full"),
    InlinePanel('speakers', label="Speakers"),
    InlinePanel('related_links', label="Related links"),
]

EventPage.promote_panels = Page.promote_panels + [
    ImageChooserPanel('feed_image'),
]