C$++$ recursively implement the following with a doubly linked list. You must use a public wrapper function to

aid your private recursive function. Do not use loops and only use return type int or bool, no void or node$*.$

Provided code includes struct node with int data, node $*$ next, node $*$ previous and class list.

Output is randomized version of this format: $3->15->6->27->41->8->33->2->2$

a$.)$ Display all the unique data that exists in the data structure and return the sum of all unique items.

b$.)$ Make a copy of the data structure, but only copy even data. Return the number of nodes copied. Do not implement this with an insert function!! Traverse only once

c$.)$ Remove every $\text{'}2\text{'}$ except the first one. REturn the number of nodes removed.Do this in a single traversal.

Do not use loops or pointer arithmetic to access elements of the array. Only use return type int or bool, no void or node$*$