python search a node in binary tree

I'm having trouble to search in the binary tree, i want to check if the root is exists but encountered an error. What am I doing wrong?

this is my full code:

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

    def printTree(self):
        if self.left:
            self.left.PrintTree()
        print(self.data),
        if self.right:
            self.right.PrintTree()

    def insert(self, data):
        """ Compare the new value with the parent node """
        if self.data:
            if data < self.data:
                if self.left is None:
                    self.left = Node(data)
                else:
                    self.left.insert(data)
            elif data > self.data:
                if self.right is None:
                    self.right = Node(data)
                else:
                    self.right.insert(data)
        else:
            self.data = data

    def is_exist(self, val):
        if val < self.data:
            if self.left is None:
                return None, None
            return self.left.exists(val, self)
        elif val > self.data:
            if self.right is None:
                return None, None
            return self.right.exists(val, self)
        else:
            return self.data

this is my search function to check if root is exist

def is_exist(self, val): if val < self.data: if self.left is None: return None, None return self.left.exists(val, self) elif val > self.data: if self.right is None: return None, None return self.right.exists(val, self) else: return self.data

this is the test:

def test_binary_tree():
    root = Node(10)
    assert root.is_exist(10)
    root.insert(4)
    assert root.is_exist(4)
    root.insert(11)
    assert root.is_exist(11)
    root.insert(3)
    assert root.is_exist(3)
    root.insert(770)
    assert root.is_exist(770)
    root.insert(523)
    assert root.is_exist(523)
    root.insert(43)

print(test_binary_tree())

the eror i got:

    return self.left.exists(val, self)
AttributeError: 'Node' object has no attribute 'exists'