{"ast_node_type":"impl","tokens":[{"end":77,"kind":"keyword","start":0,"text":"mut"}]}
    mut named_field: impl FnMut(&mut Completions, hir::Field, hir::Type<'_>),
    receiver: &hir::Type<'_>,
    mut tuple_index: impl FnMut(&mut Completions, usize, hir::Type<'_>),