Macro std_tools::index

macro_rules! index {
    () => { ... };
    (
      $Name : ident as $Alias : ident,
      $( , $( $Rest : tt )* )?
    ) => { ... };
    (
      $Name : ident
      $( , $( $Rest : tt )* )?
    ) => { ... };
}

Index of items.