BinarySearchTree implementation in Python 3.5.2, Python 3

Language: Layout:

#python 3.5.2

class Node:
    def __init__(self, data, left = None, right = None):
        self.left = left
        self.right = right
        self.data = data

class BST:
    def __init__(self, datatype):
        self.__datatype = datatype
        self.__root = None
        
    def exist(self, key):
        if self.__root == None:
            return False
        if not isinstance(key, self.__datatype):
            raise TypeError
        temp = self.__root
        while temp != None:
            if key == temp.data:
                return True
            elif key > temp.data:
                temp = temp.right
            elif key < temp.data:
                temp = temp.left
        return False
        
        
    def insert(self, data):
        if not isinstance(data, self.__datatype):
            raise TypeError
        if self.exist(data):
            return False
        if self.__root == None:
            self.__root = Node(data);
            return True
        p = self.__root
        q = p
        while p != None:
            q = p
            if data > p.data:
                p = p.right
            elif data < p.data:
                p = p.left
        if data > q.data:
            q.right = Node(data)
        elif data < q.data:
            q.left = Node(data)
        return True
    
    def insert_recursively(self, data):
        if not isinstance(data, self.__datatype):
            raise TypeError
        q = self.__root
        p = self.__root
        return self.__insert_recursively(data, q, p)
        
    def __insert_recursively(self, data, q, p):
        if p == None:
            if data > q.data:
                q.right = Node(data)
            elif data < q.data:
                q.left = Node(data)
            return True
        if data == p.data:
            return False
        if data > p.data:
            return self.__insert_recursively(data, p, p.right)
        if data < p.data:
            return self.__insert_recursively(data, p, p.left)
        
bst = BST(int)
bst.insert(4)
bst.insert(9)
bst.insert_recursively(5)
print(bst.exist(5))

[ + ] Show input
Absolute running time: 0.21 sec, cpu time: 0.19 sec, memory peak: 6 Mb, absolute service time: 0,22 sec