lowest common ancestor in a binary search tree and binary tree code example

Example: lowest common ancestor in a binary tree

#lca in a binary tree
def lca(root,a,b):
	if root in (None,a,b):
		return root
	left_side=lca(root.left,a,b)
	right_side=lca(root.right,a,b)
	if left_side and right_side:
		return root
	return left_side or right_side