text: 
  class PngFactory {
    createPng(pngOptions) {
      if (!this.PNG_) {
        this.PNG_ = require('pngjs').PNG;
      }
  
      return new this.PNG_(pngOptions);
    }
  
    pixelmatch() {
      if (!this.pixelmatch_) {
        this.pixelmatch_ = require('pixelmatch');
      }
      return this.pixelmatch_.apply(null, arguments);
    }
  }
  
  module.exports = PngFactory;
  