Function page_lines 

pub(super) fn page_lines(
    parsed_impl: &ParsedImpl,
    params: &[(&str, &str)],
) -> Vec<String>

The page lines of a field method’s block: @rdname its topic (topic) with the @param lines of params the page needs, or, on a topic the author names with the impl’s @rdname, @order NaN and no @param lines: the topic’s own block documents the arguments, and a later block’s @param would replace its text (#1590).