Macro machine::dynamic_machine

macro_rules! dynamic_machine {
    ( $machine:ident($state:ty) {
    {
      initial: $initial:expr,
      error:   $error:expr
    }

    attributes {
      $($name:ident : $t:ty),*
    }

    $(
    event[$($def:tt)*] {
      $($tokens:tt)*
    }
    )*
  }) => { ... };
}