Macro const_type::Const

macro_rules! Const {
    (
    $Visibility:vis $NameSpace:ident: $Type:ty
    {
      $(  $Constant:ident               =   $Value:expr$(,)*    )*
    }
  ) => { ... };
    (
    $Visibility:vis $NameSpace:ident
    {
      $(  $Constant:ident               =   $Value:expr$(,)*    )*
    }
  ) => { ... };
}