transform( json, jst, format, opts, theme, curFmt ) {
    if (this.opts.freezeBreaks) {
      jst = freeze(jst);
    }
    const eng = require(`../renderers/${theme.engine}-generator`);
    let result = eng.generate(json, jst, format, curFmt, opts, theme);
    if (this.opts.freezeBreaks) {
      result = unfreeze(result);
    }
    return result;
  }
Perform a single resume resume transformation using string-based inputs
  and outputs without touching the local file system.
  @param json A FRESH or JRS resume object.
  @param jst The stringified template data
  @param format The format name, such as "html" or "latex"
  @param cssInfo Needs to be refactored.
  @param opts Options and passthrough data.