def browse(request, parent_page_id=None):
    # Find parent page
    if parent_page_id:
        parent_page = get_object_or_404(Page, id=parent_page_id)
    else:
        parent_page = Page.get_first_root_node()

    # Get children of parent page
    pages = parent_page.get_children()

    # Filter them by page type
    # A missing or empty page_type parameter indicates 'all page types' (i.e. descendants of wagtailcore.page)
    page_type_string = request.GET.get('page_type') or 'wagtailcore.page'
    if page_type_string != 'wagtailcore.page':
        try:
            desired_classes = page_models_from_string(page_type_string)
        except (__HOLE__, LookupError):
            raise Http404

        # restrict the page listing to just those pages that:
        # - are of the given content type (taking into account class inheritance)
        # - or can be navigated into (i.e. have children)
        choosable_pages = filter_page_type(pages, desired_classes)
        descendable_pages = pages.filter(numchild__gt=0)
        pages = choosable_pages | descendable_pages
    else:
        desired_classes = (Page, )

    can_choose_root = request.GET.get('can_choose_root', False)

    # Parent page can be chosen if it is a instance of desired_classes
    parent_page.can_choose = (
        issubclass(parent_page.specific_class or Page, desired_classes) and
        (can_choose_root or not parent_page.is_root())
    )

    # Pagination
    # We apply pagination first so we don't need to walk the entire list
    # in the block below
    paginator, pages = paginate(request, pages, per_page=25)

    # Annotate each page with can_choose/can_decend flags
    for page in pages:
        if desired_classes == (Page, ):
            page.can_choose = True
        else:
            page.can_choose = issubclass(page.specific_class or Page, desired_classes)

        page.can_descend = page.get_children_count()

    # Render
    return render_modal_workflow(
        request,
        'wagtailadmin/chooser/browse.html', 'wagtailadmin/chooser/browse.js',
        shared_context(request, {
            'parent_page': parent_page,
            'pages': pages,
            'search_form': SearchForm(),
            'page_type_string': page_type_string,
            'page_type_names': [desired_class.get_verbose_name() for desired_class in desired_classes],
            'page_types_restricted': (page_type_string != 'wagtailcore.page')
        })
    )
dataset/ETHPy150Open torchbox/wagtail/wagtail/wagtailadmin/views/chooser.py/browse