pub trait Printer<W: Write> {
fn set_style(&mut self, style: Style);
fn set_output_handle(&mut self, w: W);
fn print_help(&mut self) -> Result<usize>;
fn print_cmd_help(&mut self, cmd: Option<Ustr>) -> Result<usize>;
fn print_section_all(&mut self) -> Result<usize>;
fn print_section(&mut self, section: Ustr) -> Result<usize>;
fn print_cmd_usage(&mut self, cmd: Option<Ustr>) -> Result<usize>;
fn print_cmd_header(&mut self, cmd: Option<Ustr>) -> Result<usize>;
fn print_cmd_footer(&mut self, cmd: Option<Ustr>) -> Result<usize>;
fn print_cmd_pos(&mut self, cmd: Option<Ustr>) -> Result<usize>;
fn print_cmd_opt(&mut self, cmd: Option<Ustr>) -> Result<usize>;
}