syntax_data: {"ast_node_type":"variable","tokens":[{"end":55,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:     let span_with_body = tcx.hir_span_with_body(fn_id);
context_before:     let body = tcx.hir_body_owned_by(fn_def);
context_after:     let return_ty_span = tcx