Macro impl_take

macro_rules! impl_take {
    (@gen($self:ident)) => { ... };
    (@gen($self:ident) {$($b:tt)*}) => { ... };
    ($(
        $(#[$meta:meta])*
        $ty:ty $([$($g:tt)*])? $({$($b:tt)*})?
    ),+ $(,)?) => { ... };
}

take like impl macro