code: function prettyLines(lines, theme) {
    if (!lines || !Array.isArray(lines)) throw new Error('Please supply an array of lines');
    if (!theme) throw new Error('Please supply a theme');
  
    function prettify(line) {
      if (!line) return null;
      return exports.line(line, theme);
    }
  
    return lines.map(prettify);
  }
docs: Prettifies multiple lines.
  
  @name prettyTrace::lines
  @function
  @param {Array.<string>} lines lines to be prettified
  @param {Object} theme theme that specifies how to prettify a trace @see prettyTrace::line
  @return {Array.<string>} the prettified lines