Write a C++ code to implement the sequence class to store double. The implementation will include a header file, an implementation file, an application file. The sequence class will include the following operartions creates a sequence with no element, int size():return the total number of elements, void start () : set context to the first element of the sequence, double current() : retrieve the current element of the sequence, void advance() : set context to the next element of the sequence, bool is_item () : return true if current context is a valid element, false otherwise, void insert(double &) : adds a new element before the current void attach(double &) :adds a new element after the current, removes the current element. Each line should include an explaination. In the application file will have the menu list and ask users to choose which operations that they want.