Find the successor to a node in a Binary Search Tree before deleting from the tree

binary-search-tree-find-successor.py

"""
Assume we have defined a BST class:
class BST(object):
    class __Node(object):
        def __init__(self, data, right=None, left=None):
            self.data = data
            self.right = right
            self.left = left

    def __init__(self, root=None):
        self.root = root
        
        
This function finds the successor that will replace the
node passed as a parameter in the Binary Search Tree.
"""

def find_successor(node):
    if node.right != None:
        current = node.right
        while current.left != None:
            current = current.left
    else:
        current = current.left

    return current