pub trait Format: Debug {
// Required methods
fn left(&self, hold: usize) -> String;
fn right(&self, hold: usize) -> String;
fn mid(&self, hold: usize) -> String;
fn left_lim(&self, hold: usize) -> String;
fn right_lim(&self, hold: usize) -> String;
fn mid_lim(&self, hold: usize) -> String;
fn cut(&self, hold: usize) -> String;
}