syntax_data: {"ast_node_type":"variable","tokens":[{"end":23,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:         let sig = self;
context_before:     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
context_after:         let FnSig { inputs_and_output: _, c_variadic, safety, abi } = sig;