docs: def _format_metric_name(self, m_name, cfunc):
          ''' Format a cacti metric name into a Datadog-friendly name '''
          try:
              aggr = CFUNC_TO_AGGR[cfunc]
          except KeyError:
              aggr = cfunc.lower()
  
          try:
              m_name = CACTI_TO_DD[m_name]
              if aggr != 'avg':
                  m_name += '.{}'.format(aggr)
              return m_name
          except KeyError:
              return "cacti.{}.{}".format(m_name.lower(), aggr)