code: private static CowFace getCowFaceByMode(final CommandLine commandLine) {
  		CowFace cowFace = null;
  		Set<String> modes = CowFace.COW_MODES.keySet();
  		for (String mode : modes) {
  			if (commandLine.hasOption(mode)) {
  				cowFace = CowFace.getByMode(mode);
  				break;
  			}
  		}
  		return cowFace;
  	}
docs: If a pre-defined cow mode has been set on the command line then use that face.
  @param commandLine The command line with user options.
  @return The cowface for the mode selected on the command line or null if no mode set.