Function rewrite_fn_base

fn rewrite_fn_base(
    context: &RewriteContext<'_>,
    indent: Indent,
    ident: Ident,
    fn_sig: &FnSig<'_>,
    span: Span,
    fn_brace_style: FnBraceStyle,
) -> Result<(String, bool, bool), RewriteError>