How to use the twemoji.default function in twemoji

async initialize () {
        /* The initialize function gets called as soon as the plugin is
         * loaded by converse.js's plugin machinery.
         */
        const { _converse } = this;
        const { ___ } = _converse;

        _converse.api.settings.update({
            'emoji_image_path': twemoji.default.base,
            'emoji_categories': {
                "smileys": ":grinning:",
                "people": ":thumbsup:",
                "activity": ":soccer:",
                "travel": ":motorcycle:",
                "objects": ":bomb:",
                "nature": ":rainbow:",
                "food": ":hotdog:",
                "symbols": ":musical_note:",
                "flags": ":flag_ac:",
                "custom": null
            },
            // We use the triple-underscore method which doesn't actually
            // translate but does signify to gettext that these strings should
            // go into the POT file. The translation then happens in the
            // template. We do this so that users can pass in their own

'emoji_category_labels': {
                "smileys": ___("Smileys and emotions"),
                "people": ___("People"),
                "activity": ___("Activities"),
                "travel": ___("Travel"),
                "objects": ___("Objects"),
                "nature": ___("Animals and nature"),
                "food": ___("Food and drink"),
                "symbols": ___("Symbols"),
                "flags": ___("Flags"),
                "custom": ___("Stickers")
            }
        });

        _converse.api.promises.add('emojisInitialized', false);
        twemoji.default.base = _converse.emoji_image_path;


        /**
         * Model for storing data related to the Emoji picker widget
         * @class
         * @namespace _converse.EmojiPicker
         * @memberOf _converse
         */
        _converse.EmojiPicker = Backbone.Model.extend({
            defaults: {
                'current_category': 'smileys',
                'current_skintone': '',
                'scroll_position': 0
            }
        });

                return _converse.use_system_emojis ? transform : text => twemoji.default.parse(transform(text), how);
            },