docs: def _redistribute_builder(self, afi='ipv4', source=None):
          """Build BGP redistribute method.
  
          Do not use this method directly.  You probably want ``redistribute``.
  
          Args:
              source (str): Source for redistributing. (connected)
              afi (str): Address family to configure. (ipv4, ipv6)
  
          Returns:
              Method to redistribute desired source.
  
          Raises:
              KeyError: if `source` is not specified.
  
          Examples:
              >>> import pynos.device
              >>> conn = ('10.24.39.203', '22')
              >>> auth = ('admin', 'password')
              >>> with pynos.device.Device(conn=conn, auth=auth) as dev:
              ...     output = dev.bgp._redistribute_builder(source='connected',
              ...     afi='ipv4')
              ...     dev.bgp._redistribute_builder(source='hodor',
              ...     afi='ipv4') # doctest: +IGNORE_EXCEPTION_DETAIL
              Traceback (most recent call last):
              AttributeError
          """
          if source == 'connected':
              return getattr(self._rbridge,
                             'rbridge_id_router_router_bgp_address_family_{0}_'
                             '{0}_unicast_default_vrf_af_{0}_uc_and_vrf_cmds_'
                             'call_point_holder_redistribute_connected_'
                             'redistribute_connected'.format(afi))
          # TODO: Add support for 'static' and 'ospf'
          else:
              raise AttributeError('Invalid source.')