func IfaceCall1(iface *Iface, fnID int, a1 lisp.Object) lisp.Object {
	return lisp.DynCall(aref(iface.itab, fnID), iface.data, a1)
}
IfaceCall1 like IfaceCall0, but for methods with arity=1.
goism:subst
package rt
import (
	"emacs/lisp"
)
func itabTag(itab lisp.Object) lisp.Object {
	return aref(itab, 0)
}
func itabMethod(itab lisp.Object, n int) lisp.Object {
	return aref(itab, n+1)
}
type Iface struct {
	itab lisp.Object
	data lisp.Object
}
func MakeIface(itab lisp.Object, data lisp.Object) *Iface {
	return &Iface{itab: itab, data: data}
}
func IfaceCall0(iface *Iface, fnID int) lisp.Object {
	return lisp.DynCall(itabMethod(iface.itab, fnID), iface.data)
}