How to use the sketch-constructor.Sketch function in sketch-constructor

function buildSketch(designInfo) {
    const newSketch = new Sketch();

    buildComponents(designInfo);
    buildFlows(designInfo, newSketch);
    buildLibrary(designInfo, newSketch);

    newSketch.build('output.sketch');
}

import { Sketch, Page, Artboard, Text, Rectangle } from 'sketch-constructor';
import * as sketchJson from 'sketch-json';
import * as fs from 'fs';

const pkg = JSON.parse(fs.readFileSync('./package.json', 'utf8'));
const buildFolder = './build';

const newSketch = new Sketch({});
const pageWelcome = new Page({
  name: 'Welcome'
});

let yPos = 0;

const addYPos = (value: number = 0) => {
  return yPos = yPos + value;
}

const textVersion = new Text({
  string: `Version: ${pkg.version}`,
  name: `Version: ${pkg.version}`,
  fontSize: 16,
  color: "#777",
  frame: {