The definition for binary search tree should be the one used in class Class definition:                                                                       A BST is a binary tree that (if not empty) also follows two storage rules regarding its nodes’ items:       ♯ For any node n of the tree, every item in n’s left subtree (LST), if not empty, is less than the item in n ♯       ♯ For any node n of the tree, every item in n’s right subtree (RST), if not empty, is greater than the item in n ● bst_insert must be iterative (NOT recursive). ● bst_remove and bst_remove_max must use the algorithm described by the suggested book authors  In btNode.h: provide prototypes for bst_insert, bst_remove and bst_remove_max.   ● In btNode.cpp: provide definition (implementation) for bst_insert, bst_remove and bst_remove_ma #ifndef BT_NODE_H #define BT_NODE_H struct btNode {    int data;    btNode* left;    btNode* right; }; // pre:  bst_root is root pointer of a binary search tree (may be 0 for //       empty tree) and portArray has the base address of an array large //       enough to hold all the data items in the binary search tree // post: The binary search tree has been traversed in-order and the data //       values are written (as they are encountered) to portArray in //       increasing positional order starting from the first element void portToArrayInOrder(btNode* bst_root, int* portArray); void portToArrayInOrderAux(btNode* bst_root, int* portArray, int& portIndex); // pre:  (none) // post: dynamic memory of all the nodes of the tree rooted at root has been //       freed up (returned back to heap/freestore) and the tree is now empty //       (root pointer contains the null address) void tree_clear(btNode*& root); // pre:  (none) // post: # of nodes contained in tree rooted at root is returned int bst_size(btNode* bst_root); // pre:  bst_root is root pointer of a binary search tree (may be 0 for //       empty tree) // post: If no node in the binary search tree has data equals insInt, a //       node with data insInt has been created and inserted at the proper //       location in the tree to maintain binary search tree property. //       If a node with data equals insInt is found, the node's data field //       has been overwritten with insInt; no new node has been created. //       (Latter case seems odd but it's to mimick update of key-associated //       data that exists in more general/real-world situations.) // write prototype for bst_insert here // pre:  bst_root is root pointer of a binary search tree (may be 0 for //       empty tree) // post: If remInt was in the tree, then remInt has been removed, bst_root //       now points to the root of the new (smaller) binary search tree, //       and the function returns true. Otherwise, if remInt was not in the //       tree, then the tree is unchanged, and the function returns false. // write prototype for bst_remove here // pre:  bst_root is root pointer of a non-empty binary search tree // post: The largest item in the binary search tree has been removed, and //       bst_root now points to the root of the new (smaller) binary search //       tree. The reference parameter, removed, has been set to a copy of //       the removed item. // write prototype for bst_remove_max here #endif