How to use the jinja2.contextfunction function in Jinja2

@jinja2.contextfunction
def collection_listing_items(context, collections, field=None):
    c = dict(context.items())
    c.update(collections=collections, field=field)
    return c

@jinja2.contextfunction
def is_watching(context, obj, user=None):
    if not user:
        user = context['request'].user
    if not hasattr(user, 'email'):
        return False
    return check_watch(obj.__class__, obj.pk, user.email)

@jinja2.contextfunction
def queue_tabnav(context):
    """
    Returns tuple of tab navigation for the queue pages.

    Each tuple contains three elements: (named_url. tab_code, tab_text)
    """
    request = context['request']
    counts = context['queue_counts']
    apps_reviewing = AppsReviewing(request).get_apps()

    # Apps.
    if acl.action_allowed(request, 'Apps', 'Review'):
        rv = [
            ('reviewers.apps.queue_pending', 'pending',
             _('Apps ({0})', counts['pending']).format(counts['pending'])),

@jinja2.contextfunction
def include_external_base64(ctx, name):
    with open(os.path.abspath(name), "rb") as f:
        encoded_string = base64.b64encode(f.read())
    return jinja2.Markup(encoded_string.decode())

    @contextfunction
    def get_list_value(self, context, model, name):
        if name in ['start_date', 'end_date']:
            original = getattr(model, name, None)
            if original:
                return utc_time_zone.localize(original).astimezone(
                    app_time_zone).strftime(DATETIME_FORMAT_SPEC)

            return original

        return super(EventAdminView, self).get_list_value(context, model, name)

@jinja2.contextfunction
def impala_addon_listing_header(context, url_base, sort_opts=None,
                                selected=None, extra_sort_opts=None,
                                search_filter=None):
    if sort_opts is None:
        sort_opts = {}
    if extra_sort_opts is None:
        extra_sort_opts = {}
    if search_filter:
        selected = search_filter.field
        sort_opts = search_filter.opts
        if hasattr(search_filter, 'extras'):
            extra_sort_opts = search_filter.extras
    # When an "extra" sort option becomes selected, it will appear alongside
    # the normal sort options.
    old_extras = extra_sort_opts
    sort_opts, extra_sort_opts = list(sort_opts), []

else:
            nation = pytz.timezone('Europe/Rome')
        nation_time = utc_time.astimezone(nation)
        return str(nation_time.day) + ' ' + dict_month[g.lan][nation_time.month] + ' ' + str(nation_time.year)
    else:
        return value.strftime(format)

def split_word_format(value, letters=30):
    if len(value) > (letters * 2):
        return value[:letters] + '<br>' + value[letters:(letters*2)] + '<br>' + value[(letters*2):]
    if len(value) &gt; letters:
        return value[:letters] + '<br>' + value[letters:]
    return value

# add some functions to jinja
app.jinja_env.globals['sorted'] = contextfunction(sorted_thing)  
app.jinja_env.globals['int'] = contextfunction(int_thing)   
app.jinja_env.globals['str'] = contextfunction(str_thing) 
app.jinja_env.globals['unicode'] = contextfunction(unicode_thing) 
app.jinja_env.globals['type'] = contextfunction(type_thing) 
app.jinja_env.globals['len'] = contextfunction(len_thing) 
app.jinja_env.globals['enumerate'] = contextfunction(enumerate_thing) 

app.jinja_env.filters['date'] = date_time_format
app.jinja_env.filters['split_word'] = split_word_format
app.jinja_env.filters['msg'] = msg_status

class RegexConverter(BaseConverter):
    def __init__(self, url_map, *items):
        super(RegexConverter, self).__init__(url_map)
        self.regex = items[0]

@jinja2.contextfunction
def filter_box_toggle(context, label=''):
    return new_context(**locals())

    @contextfunction
    def capdl_declare_ipc_buffer(context, cap_symbol, symbol):
        return TutorialFunctions.capdl_declare_frame(context, cap_symbol, symbol)

@contextfunction
def full_url(context, path, safe=None):
    """
    Returns the full url given a partial path.
    """
    return context['site'].full_url(path, safe)