code: def genl_family_add_grp(family, id_, name):
      
      grp = genl_family_grp(id_=id_, name=name)
      nl_list_add_tail(grp.list_, family.gf_mc_grps)
      return 0
docs: https://github.com/thom311/libnl/blob/libnl3_2_25/lib/genl/family.c#L366.
  
      Positional arguments:
      family -- Generic Netlink family object (genl_family class instance).
      id_ -- new numeric identifier (integer).
      name -- new human readable name (string).
  
      Returns:
      0