SV *
topdl(klass, arg1, ...)
  SV *klass;
  SV *arg1;
  CODE:
    if (items > 2 ||
      (!SvROK(arg1) && SvTYPE(arg1) < SVt_PVAV) ||
      (SvROK(arg1) && SvTYPE(SvRV(arg1)) == SVt_PVAV)
    ) {
      SP -= items; PUSHMARK(SP); SPAGAIN; /* these pass this set of args on */
      int retvals = perl_call_method("new", G_SCALAR);
      SPAGAIN;
      if (retvals != 1) barf("new returned no values");
      RETVAL = POPs;
    } else if (SvROK(arg1) && SvOBJECT(SvRV(arg1))) {
      RETVAL = arg1;
    } else {
      barf("Can not convert a %s to a %s", sv_reftype(arg1, 1), SvPV_nolen(klass));
    }
    SvREFCNT_inc(RETVAL);
  OUTPUT:
    RETVAL