How to use the mapshaper.internal function in mapshaper

'use strict';
var path = require('path');
var settings = require('./settings');
var fs = require('fs-extra');
var fileUrl = require('file-url');
var electron = require('electron');
var BrowserWindow = electron.BrowserWindow;
var turf = require('@turf/turf');
var Tin = require('../common/js/tin');
var wkt = require('wellknown');
var isClockwise = turf.booleanClockwise;
const {ipcMain} = require('electron');
var internal = require('mapshaper').internal;

settings.init();

var mapFolder;
var tileFolder;
var focused;
var tinObject;

var mapedit = {
    init: function() {
        var saveFolder = settings.getSetting('saveFolder');
        mapFolder = saveFolder + path.sep + 'maps';
        fs.ensureDir(mapFolder, function(err) {});
        tileFolder = saveFolder + path.sep + 'tiles';
        fs.ensureDir(tileFolder, function(err) {});
        focused = BrowserWindow.getFocusedWindow();