syntax_data: {"ast_node_type":"function","tokens":[{"end":64,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
context_before: impl<'tcx> fmt::Display for Discr<'tcx> {
context_after:         match *self.ty.kind() {