syntax_data: {"ast_node_type":"other","tokens":[{"end":95,"kind":"keyword","start":0,"text":"FnHeader"}]}
source_snippet:             FnHeader { c_variadic: self.c_variadic(), safety: self.safety(), abi: self.abi() };
context_before:         let hdr =
context_after:         (self.map_bound(|sig| FnSigTys { inputs_and_output: sig.inputs_and_output }), hdr)