code: def _format_eval_result(value, show_stdv=True):
      
      if len(value) == 4:
          return '%s\'s %s: %g' % (value[0], value[1], value[2])
      elif len(value) == 5:
          if show_stdv:
              return '%s\'s %s: %g + %g' % (value[0], value[1], value[2], value[4])
          else:
              return '%s\'s %s: %g' % (value[0], value[1], value[2])
      else:
          raise ValueError("Wrong metric value")
docs: Format metric string.