Macro opcodes 

macro_rules! opcodes {
    (
        $(#[$meta:meta])*
        $enum_name:ident => $fork:ident {
            $(
                $opcode:literal => $name:ident {
                    gas: $gas:literal,
                    inputs: $inputs:literal,
                    outputs: $outputs:literal,
                    description: $description:literal,
                    introduced_in: $introduced:ident,
                    group: $group:ident,
                    eip: $eip:expr,
                    gas_history: [$($gas_fork:ident => $gas_cost:literal),*],
                }
            ),* $(,)?
        }
    ) => { ... };
}

Macro to generate opcode enums with metadata