TypeTag:
    | {
        bool: null | true;
    }
    | {
        u8: null | true;
    }
    | {
        u64: null | true;
    }
    | {
        u128: null | true;
    }
    | {
        address: null | true;
    }
    | {
        signer: null | true;
    }
    | {
        vector: TypeTag;
    }
    | {
        struct: StructTag;
    }
    | {
        u16: null | true;
    }
    | {
        u32: null | true;
    }
    | {
        u256: null | true;
    }

Sui TypeTag object. A decoupled 0x...::module::Type<???> parameter.