Macro futures_error_chain::future_chain_processed

macro_rules! future_chain_processed {
    (
        types {}
        $( $rest: tt )*
    ) => { ... };
    (
        types {
            $error_name:ident, $error_kind_name:ident,
            $future_ext_name:ident, $future_name:ident;
        }
        $( $rest: tt )*
    ) => { ... };
    (
        types {
            $error_name:ident, $error_kind_name:ident,
            $future_ext_name:ident;
        }

    ) => { ... };
}