Binary search tree, no recursion.

BST.py

"""Python3 function to search a given key in a given BST."""


class Node:
    left: 'Node' = None
    right: 'Node' = None

    def __init__(self, key):
        self.key = key

    def insert(self, key):
        if key == self.key:
            raise ValueError

        if key < self.key:
            if self.left:
                self.left.insert(key)
            else:
                self.left = Node(key)

        elif key > self.key:
            if self.right:
                self.right.insert(key)
            else:
                self.right = Node(key)

        return self

    def search(self, key):
        if self.key == key:
            return self

        if self.key < key:
            if not self.right:
                raise FileNotFoundError
            return self.right.search(key)

        if not self.left:
            raise FileNotFoundError
        return self.left.search(key)


if __name__ == '__main__':
    root = Node(50)
    root.insert(30)
    root.insert(20)
    root.insert(40)
    root.insert(70)
    root.insert(60)
    root.insert(80)

    # Key to be found
    key = 6

    # Searching in a BST
    if root.search(key) is None:
        print(key, "not found")
    else:
        print(key, "found")

    key = 60

    # Searching in a BST
    if root.search(key) is None:
        print(key, "not found")
    else:
        print(key, "found")