Please help code in C++ and provide explanation thank you.

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//BinarySearchTree.h

#ifndef BINARY_SEARCH_TREE_H

#define BINARY_SEARCH_TREE_H

#include // for std::cout

namespace BST_NS

{

template

class BinarySearchTree; //forward declaration

template

class TreeNode {

public:

TreeNode( ) : data(NULL), leftLink(NULL), rightLink(NULL) {}

TreeNode(T theData, TreeNode* left, TreeNode* right)

: data(theData), leftLink(left), rightLink(right) {}

friend class BinarySearchTree;

private:

T data;

TreeNode* leftLink;

TreeNode* rightLink;

};

// supply the pre and post conditions for each method

template

class BinarySearchTree {

private:

TreeNode *root;

int tree_size;

public:

// default ctor

BinarySearchTree() : root(NULL), tree_size(0) {}

// copy ctor

BinarySearchTree(const BinarySearchTree& other);

// virtual dtor

virtual ~BinarySearchTree();

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//BinarySearchTree.cpp

#include "BinarySearchTree.h"

/**Please help providing a correct implementation for the following:

// default constructor, also, do I need a copyTree() for this?

BinarySearchTree() : root(NULL), tree_size(0) {}

// copy constructor

BinarySearchTree(const BinarySearchTree& other);

// virtual destructor

virtual ~BinarySearchTree();

**/