code: func (v *Assistant) SetPageType(page IWidget, ptype AssistantPageType) {
  	C.gtk_assistant_set_page_type(v.native(), page.toWidget(),
  		C.GtkAssistantPageType(ptype))
  }
docs: // TODO: gtk_assistant_set_forward_page_func
  // SetPageType is a wrapper around gtk_assistant_set_page_type().