Macro lazy_format 

lazy_format!() { /* proc-macro */ }

Lazy format macro

lazy_format! is syntax sugar of Display.

The first form of lazy_format! receives closure as the only one argument.

lazy_format!(|f| ...);

it expands to:

Display(move |f| ...);

The second form of lazy_format! has a syntax identical to the syntax of format!. See fmt for more information.

lazy_format!("...", arg0, arg1, ...);

it expands to:

Display(move |f| write!(f, "...", arg0, arg1, ...));