I need code for this

23. (10 points) The nodes of a binary tree containing strings can be represented in C++ as follows: struct BTNode { // binary tree node string data; // node data BTNode * left; // left subtree BTNode * right; // right subtree An internal node in a binary tree is one that is not a leaf, i.e., an internal node is one that has at least one child. Complete the following function so it returns the number of internal nodes in a binary tree. Hint: Recursion is your friend. / = # of internal nodes in tree with given root int ninternal(BTNode *root) {