{"ast_node_type":"impl","tokens":[{"end":61,"kind":"keyword","start":0,"text":"mut"}]}
    mut peel_casts: impl FnMut() -> (&'tcx Expr<'tcx>, bool),
    orig_expr: &'tcx Expr<'tcx>,
) -> Option<(TyAndLayout<'tcx>, TyAndLayout<'tcx>, Expr<'tcx>)> {