{"ast_node_type":"other","tokens":[{"end":60,"kind":"keyword","start":0,"text":"self.lang_items().get(lang_item).unwrap_or_else(||"}]}
        self.lang_items().get(lang_item).unwrap_or_else(|| {
    pub fn require_lang_item(self, lang_item: LangItem, span: Span) -> DefId {
            self.dcx().emit_fatal(crate::error::RequiresLangItem { span, name: lang_item.name() });