Macro define_into_enum 

macro_rules! define_into_enum {
    {
    $(#[$attr:meta])*
    $vis:vis enum $name:ident $(< $generic:lifetime >)* {
      $(#[$variant_attr1:meta])*
      $variant1:ident ($type1:ty),
      $(
        $(#[$variant_attr:meta])*
        $variant:ident ($type:ty),
      )*
    }
    $into:pat,
    $output:expr
  } => { ... };
}