modulusTooBigChecker = (inputKey, span, modName='mod') => args => {
    let r = args.context.get('Input Range ' + inputKey);
    let d = args.context.get('Input Default ' + inputKey);
    if (r !== undefined && r.length > span) {
        return `${modName}\ntoo\nbig`;
    }
    if (r === undefined && d !== undefined && d > 1<<span) {
        return `${modName}\ntoo\nbig`;
    }
    return undefined;
}
@param {!string} inputKey
@param {!int} span
@param {!string=} modName
@returns {!function(!GateCheckArgs) : (undefined|!string)}