Delete a node ins a BST

gistfile1.py

def transplant(root, node, newone):
  if newone:
    newone.parent = node.parent
  if node.parent:
    if node.parent.left == node:
      node.parent.left = newone
    else:
      node.parent.right = newone
  else:
    root = newone
  return root

def delete(root, node):
  if node.left is None:
    root = transplant(root, node, node.right)
  elif node.right is None:
    root = transplant(root, node, node.left)
  else:
   # TODO(sahid): Just crazy to understand!