m4_dnl hm_arg_nullptr(<type>,<arg>) pointer of type type, must be null
m4_dnl hm_arg_int(<arg>) signed integer
m4_dnl hm_arg_fdset_io(<arg>,<max>) fd_set, max bit set is in max
m4_dnl hm_arg_nullptr(<type>,<arg>) pointer of type type, must be null
m4_dnl hm_arg_int(<arg>) signed integer
m4_dnl hm_arg_fdset_io(<arg>,<max>) fd_set, max bit set is in max