syntax_data: {"ast_node_type":"other","tokens":[{"end":33,"kind":"keyword","start":0,"text":"f.write_str(match"}]}
source_snippet:         f.write_str(match *self {
context_before:     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
context_after:             Variance::Covariant => "+",