{"ast_node_type":"other","tokens":[{"end":32,"kind":"keyword","start":0,"text":"///"}]}
    /// trait, if it is defined.
    /// Given a [`ty::ClosureKind`], get the [`DefId`] of its corresponding `Fn`-family
    pub fn fn_trait_kind_to_def_id(self, kind: ty::ClosureKind) -> Option<DefId> {