function stringifyJSON(obj) {
// implement here
}
// These two logs should match:
console.log(stringifyJSON({ x: 5, y: 6, z: [1, true, {'hi': 'bye'}, function(){}] }));
console.log(JSON.stringify({ x: 5, y: 6, z: [1, true, {'hi': 'bye'}, function(){}] }));