Function s3_method_doc 

fn s3_method_doc(
    lines: &mut Vec<String>,
    parsed_impl: &ParsedImpl,
    generic: &str,
    on_page: bool,
    register: bool,
    params: &[(&str, &str)],
)

The roxygen block of an S3 or env field method <generic>.<Class>: on the class’s topic (page_lines) for an exported class with a page, else no page. The method is registered (S3method()) when register is set.