You're missing: 5. Write a function `serialize_vec3(vec: Vec3) -> String`, and call it in the places you want to serialize a Vec3. The body of the function can

You're missing: 5. Write a function `serialize_vec3(vec: Vec3) -> String`, and call it in the places you want to serialize a Vec3. The body of the function can convert it to a new type that #derives Serializable, or it can implement the Serializable trait directly.