human
I am working on the file "Python/Chapter-07/AVL-Trees.ipynb".
The first task is:
AVL Trees
This notebook implements
AVL trees.  The set $\mathcal{A}$ of AVL trees is defined inductively:

$\texttt{Nil} \in \mathcal{A}$.
$\texttt{Node}(k,v,l,r) \in \mathcal{A}\quad$  iff 
$\texttt{Node}(k,v,l,r) \in \mathcal{B}$,
$l, r \in \mathcal{A}$, and
$|l.\texttt{height}() - r.\texttt{height}()| \leq 1$.


According to this definition, an AVL tree is an ordered binary tree
such that for every node $\texttt{Node}(k,v,l,r)$ in this tree the height of the left subtree $l$ and the right
subtree  $r$ differ at most by one. 
The class AVLTree represents the nodes of an AVL tree.  This class has the following member variables:

mKey is the key stored at the root of the tree,
mValue is the values associated with this key,
mLeft is the left subtree, 
mRight is the right subtree, and
mHeight is the height.

The constructor __init__ creates the empty tree.
Can you write Python code for it?
assistant
#Here is the Python code you requested.

class AVLTree:
    def __init__(self):
        self.mKey    = None
        self.mValue  = None
        self.mLeft   = None
        self.mRight  = None
        self.mHeight = 0