code: func (v *SList) Foreach(fn func(ptr unsafe.Pointer)) {
  	for l := v; l != nil; l = l.Next() {
  		fn(unsafe.Pointer(l.native().data))
  	}
  }
docs: // Foreach acts the same as g_slist_foreach().
  // No user_data argument is implemented because of Go clojure capabilities.