human
Write me a the Python code you requested given the following:
I am working on the file "Python/Chapter-06/2-3-Trees-Visualization.ipynb".
The first task is:
The class Three represents a 3-node of the form $\texttt{Three}(l, k_L, m, k_R, r)$.  It manages 5 member variables:
  - mLeft   is the left subtree $l$,
  - mKeyL   is the left key $k_L$,
  - mMiddle is the middle subtree $m$,
  - mKeyR   is the right key $k_r$,
  - mRight  is the right subtree.
Can you write Python code for it?
assistant
#Here is the Python code you requested.

class Three(TwoThreeTree):
    def __init__(self, left, keyL, middle, keyR, right):
        TwoThreeTree.__init__(self)
        self.mLeft   = left
        self.mKeyL   = keyL
        self.mMiddle = middle
        self.mKeyR   = keyR
        self.mRight  = right

    def __str__(self):
        return self._make_string(['mLeft', 'mKeyL', 'mMiddle', 'mKeyR', 'mRight'])        

    def isThree(self):
        return True