docs: def family_constructor(c):
      """https://github.com/thom311/libnl/blob/libnl3_2_25/lib/genl/family.c#L37.
  
      Positional arguments:
      c -- nl_object-derived class instance.
      """
      family = c
      if not hasattr(family, 'gf_ops'):
          setattr(family, 'gf_ops', nl_list_head(container_of=family))
      if not hasattr(family, 'gf_mc_grps'):
          setattr(family, 'gf_mc_grps', nl_list_head(container_of=family))
      nl_init_list_head(family.gf_ops)
      nl_init_list_head(family.gf_mc_grps)