@Override
  public void println(int logLevel, String tag, String msg) {
    for (Printer printer : printers) {
      printer.println(logLevel, tag, msg);
    }
  }
Constructor, pass printers in and will use all these printers to print the same logs.

@param printers the printers used to print the same logs
xlog/src/main/java/com/elvishew/xlog/printer/PrinterSet.java