syntax_data: {"ast_node_type":"variable","tokens":[{"end":46,"kind":"keyword","start":0,"text":"let"}]}
source_snippet:                 let fn_ty = self.thir[fun].ty;
context_before:             ExprKind::Call { fun, ty: _, args: _, from_hir_call: _, fn_span: _ } => {
context_after:                 let sig = fn_ty.fn_sig(self.tcx);