binary tree python implementation

binary_tree.py

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


class BinarySeachTree:

    def __init__(self, root=None):
        self.root = root

    def put(self, key, value):
        self.root = self.__put(key, value, self.root)

    def __put(self, key, value, node):
        if node == None:
            return Node(key=key, value=value)
        if key < node.key:
            node.left = self.__put(key, value, node.left)
        elif key > node.key:
            node.right = self.__put(key, value, node.right)
        elif node.key is key:
            node.value = value
        return node

    def get(self, key):
        return self.__get(key, self.root)

    def __get(self, key, node):
        if node == None:
            return None
        if key < node.key:
            return self.__get(key, node.left)
        elif key > node.key:
            return self.__get(key, node.right)
        elif key is node.key:
            return node.value

    def min(self, node=None):
        node = node or self.root
        if node.left == None:
            return node.value
        return self.min(node.left)

    def max(self, node=None):
        node = node or self.root
        if node.right == None:
            return node.value
        return self.max(node.right)

    def delete(self, key):
        pass

tree = BinarySeachTree()
tree.put('H', 'H')
tree.put('C', 'C')
tree.put('I', 'I')
tree.put('B', 'B')

print tree.get('H')
print tree.get('C')
print tree.get('I')
print tree.get('B')
print tree.get('Z')
tree.put('Z', 'Z')

print tree.min()
print tree.max()