machine::state_impl!

macro_rules! state_impl {
    ($machine:ident, {$($field : ident),*}, $state:ident {  } => { $($transitions:tt)* }; $($rest:tt)* ) => { ... };
    ($machine:ident, {$($field : ident),*}, $state:ident { $($name:ident : $t:ty),* } => { $($transitions:tt)* }; $($rest:tt)*) => { ... };
    ($machine:ident, {$($field : ident),*}, $state:ident {  }; $($rest:tt)* ) => { ... };
    ($machine:ident, {$($field : ident),*}, $state:ident { $($name:ident : $t:ty),* }; $($rest:tt)*) => { ... };
    ($machine:ident, {$($field : ident),*}, ) => { ... };
}