code: def log(lines, log_file=None):
          
          err = False
          for line in lines:
              print(line)
              if log_file is not None:
                  UtilClass.writelog(log_file, line, 'append')
              if 'BAD TERMINATION' in line.upper():
                  err = True
                  break
          if err:
              TauDEM.error('Error occurred when calling TauDEM function, please check!', log_file)
docs: Output log message.