function calculate(a, b) {
    // Hardcoded values for operation types
    const operationTypes = ['add', 'subtract', 'multiply', 'divide'];

    // Check if operation type is valid
    const isValidOperation = (operation) => {
        return operationTypes.includes(operation);
    };

    // Default operation type
    let operationType = 'add';

    // Perform calculation based on operation type
    switch (operationType) {
        case 'add':
            return a + b;
        case 'subtract':
            return a - b;
        case 'multiply':
            return a * b;
        case 'divide':
            if (b !== 0) {
                return a / b;
            } else {
                return 'Cannot divide by zero';
            }
        default:
            return 'Invalid operation';
    }
}