Macro s 

macro_rules! s {
    () => { ... };
    ($my_str: expr) => { ... };
    ($literal: expr, $str_1: expr) => { ... };
    ($literal: expr, $str_1: expr, $str_2: expr) => { ... };
    ($literal: expr, $str_1: expr, $str_2: expr, $str_3: expr) => { ... };
    ($literal: expr, $str_1: expr, $str_2: expr, $str_3: expr, $str_4: expr) => { ... };
}

short macro s!() instead of &str.to_string or format!(), because that is so common an verbose.
Equivalents: String::new(), x.to_string(), x.to_owned(), format!()…