Macro flags 

macro_rules! flags {
    () => { ... };
    ($(#[$attributes:meta])* $visibility:vis enum $identifier:ident: $t:ty { $($(#[$variant:meta])* $k:ident),+ $(,)* } $($next:tt)*) => { ... };
    (@count_and_gen $(#[$attributes:meta])* $visibility:vis enum $identifier:ident: $t:ty
        { $($accumulated:tt)* }
        [ ($(#[$variant_meta:meta])* $current:ident) $(($($rest_items:tt)*))* ]
        [ $($counter:tt)* ]
        $($next:tt)*
    ) => { ... };
    (@count_and_gen $(#[$attributes:meta])* $visibility:vis enum $identifier:ident: $t:ty
        { $($accumulated:tt)* }
        [ ]
        [ $($counter:tt)* ]
        $($next:tt)*
    ) => { ... };
    (@bit_value []) => { ... };
    (@bit_value [+]) => { ... };
    (@bit_value [+ +]) => { ... };
    (@bit_value [+ + +]) => { ... };
    (@bit_value [+ + + +]) => { ... };
    (@bit_value [+ + + + +]) => { ... };
    (@bit_value [+ + + + + +]) => { ... };
    (@bit_value [+ + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    (@bit_value [+ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + +]) => { ... };
    ($(#[$attributes:meta])* $visibility:vis enum $identifier:ident: $t:ty { $($(#[$variant:meta])*$k:ident = $v:expr),* $(,)* } $($next:tt)*) => { ... };
}