Naive Python Tree Implementation for demonstration purposes.

tree_node.py

class Node:
    '''
    Simple implementation of a tree.  Functions for add(), search(), and size().
    '''

    def __init__(self, value):
        self.value = value
        self.left = None
        self.right = None

    def add(self, data):
        '''Add data to tree.  Internally creates a new node.'''
        if data < self.value:
            if self.left is None:
                self.left = Node(data)
            else: 
                self.left.add(data)
        else:
            if self.right is None:
                self.right = Node(data)
            else:
                self.right.add(data)

    def search(self, query):
        '''Return node with matching value.'''
        if query == self.value:
            return self
        elif query < self.value:
            if self.left is None:
                raise Exception('Node not found')
            return self.left.search(query)
        else:
            if self.right is None:
                raise Exception('Node not found')
            return self.right.search(query)

    def size(self):
        '''Get the size of all nodes.'''
        stack = []
        count = 1               # 1 for this node

        if self.left:
            stack.append(self.left)
            count += 1
        if self.right:
            stack.append(self.right)
            count += 1
        
        while len(stack) != 0:
            node = stack.pop(0)
            if node.left:
                stack.append(node.left)
                count += 1
            if node.right:
                stack.append(node.right)
                count += 1

        return count