code: public static Printer create(Printer printer, String prefix) {
          if (prefix == null || prefix.equals("")) {
              return printer;
          }
          return new PrefixPrinter(printer, prefix);
      }
docs: Creates a new PrefixPrinter.
  
  <p>If prefix is null or empty, the provided printer is returned, rather
  than making a prefixing printer.