code: public Predictor label(String itran, String ircvr)
      {
          input.add(new CommandLine<>(LABEL, 20, itran, ircvr));
          return this;
      }
docs: The LABEL command contains alphanumeric information used to describe the
  system location on both the input and output.
  
  @param itran is an array of 20 alphanumeric characters used to describe
  the transmitter location.
  @param ircvr is an array of 20 alphanumeric characters used to describe
  the receiver location.
  @return