Hi, I can't figure out the count_unique function. Here is the method. The Data Structures that you can use are below. Note: YOU CAN ONLY USE THE DATA STRUCTURES PROVIDED (no using python Lists or anything):

 def count_unique(self) -> int: """ Returns the count of unique values stored in the tree. If all values stored in the tree are distinct (no duplicates), this method will return the same result as the size() method. """ Code here (python)

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 class Stack: """ Class implementing STACK ADT. Supported methods are: push, pop, top, is_empty DO NOT CHANGE THIS CLASS IN ANY WAY YOU ARE ALLOWED TO CREATE AND USE OBJECTS OF THIS CLASS IN YOUR SOLUTION """ def __init__(self): """ Initialize empty stack based on Python list """ self._data = [] def push(self, value: object) -> None: """ Add new element on top of the stack """ self._data.append(value) def pop(self) -> object: """ Remove element from top of the stack and return its value """ return self._data.pop() def top(self) -> object: """ Return value of top element without removing from stack """ return self._data[-1] def is_empty(self): """ Return True if the stack is empty, return False otherwise """ return len(self._data) == 0 def __str__(self): """ Return content of the stack as a string (for use with print) """ data_str = [str(i) for i in self._data] return "STACK: { " + ", ".join(data_str) + " }" class Queue: """ Class implementing QUEUE ADT. Supported methods are: enqueue, dequeue, is_empty DO NOT CHANGE THIS CLASS IN ANY WAY YOU ARE ALLOWED TO CREATE AND USE OBJECTS OF THIS CLASS IN YOUR SOLUTION """ def __init__(self): """ Initialize empty queue based on Python list """ self._data = [] def enqueue(self, value: object) -> None: """ Add new element to the end of the queue """ self._data.append(value) def dequeue(self) -> object: """ Remove element from the beginning of the queue and return its value """ return self._data.pop(0) def is_empty(self): """ Return True if the queue is empty, return False otherwise """ return len(self._data) == 0 def __str__(self): """ Return content of the stack as a string (for use with print) """ data_str = [str(i) for i in self._data] return "QUEUE { " + ", ".join(data_str) + " }" class TreeNode: """ Binary Search Tree Node class DO NOT CHANGE THIS CLASS IN ANY WAY """ def __init__(self, value: object) -> None: """ Init new Binary Search Tree DO NOT CHANGE THIS METHOD IN ANY WAY """ self.value = value # to store node's data self.left = None # pointer to root of left subtree self.right = None # pointer to root of right subtree def __str__(self): return str(self.value) class BST: def __init__(self, start_tree=None) -> None: """ Init new Binary Search Tree DO NOT CHANGE THIS METHOD IN ANY WAY """ self.root = None # populate BST with initial values (if provided) # before using this feature, implement add() method if start_tree is not None: for value in start_tree: self.add(value) def __str__(self) -> str: """ Return content of BST in human-readable form using in-order traversal DO NOT CHANGE THIS METHOD IN ANY WAY """ values = [] self._str_helper(self.root, values) return "TREE pre-order { " + ", ".join(values) + " }" def _str_helper(self, cur, values): """ Helper method for __str__. Does pre-order tree traversal DO NOT CHANGE THIS METHOD IN ANY WAY """ # base case if not cur: return # store value of current node values.append(str(cur.value)) # recursive case for left subtree self._str_helper(cur.left, values) # recursive case for right subtree self._str_helper(cur.right, values)