markdownify() {

    const MDIN =  txt  => MD(txt || '' ).replace(/^\s*<p>|<\/p>\s*$/gi, '');

    const trx = function( key, val ) {
      if (key === 'summary') {
        return MD(val);
      }
      return MDIN(val);
    };

    return this.transformStrings(['skills','url','start','end','date'], trx);
  }
Create a copy of this resume in which all fields have been interpreted as
  Markdown.