const void X::y(){
//I think it assure's that even if it returns a pointer or a refrence it cant be changed
//such that the pointee or referenced item will be changed.
//Plese Correct me if I am wrong.
}
void X::y() const{
//Does not alter any data of the class
//so can't call any non-const member function too
//Plese Correct me if I am wrong.
}