human
I am working on the file "Python/Set.ipynb".
The first task is:
Sets implemented as AVL Trees
This notebook implements <em style="color:blue;">sets</em> as <a href="https://en.wikipedia.org/wiki/AVL_tree">AVL trees</a>.  The set $\mathcal{A}$ of <em style="color:blue;">AVL trees</em> is defined inductively:

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


According to this definition, an AVL tree is an <em style="color:blue;">ordered binary tree</em>
such that for every node $\texttt{Node}(k,l,r)$ in this tree the height of the left subtree $l$ and the right
subtree  $r$ differ at most by one. 
The class Set 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,
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 program for it?
 Write me a the Python program you requested?
assistant
#Here is the Python program you requested.

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