{"ast_node_type":"function","tokens":[{"end":78,"kind":"keyword","start":0,"text":"fn"}]}
fn reduce_impl_span_to_impl_keyword(sm: &SourceMap, impl_span: Span) -> Span {
/// `source_map` functions and this function to something more robust.
    let impl_span = sm.span_until_char(impl_span, '<');