macro_rules! histogram {
    ($stat:expr, $val:expr) => { ... };
    ($stat:path, $val:expr) => { ... };
    ($stat:expr, $val:expr; $( $key:expr => $value:expr ), *) => { ... };
    ($stat:path, $val:expr; $( $key:expr => $value:expr ), *) => { ... };
}
Expand description

Report a value in a histogram