Function push_param_filler 

fn push_param_filler(
    lines: &mut Vec<String>,
    r_params: &str,
    doc_tags: &[String],
    page: &str,
    choice_docs: Option<&HashMap<String, String>>,
)

Push one #' @param name text line per generated_params entry: the choice text for a choice parameter, (undocumented) otherwise (so R CMD check codoc sees every formal in \usage documented).