human
Give 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 Onerepresents a 1-node.  These are nodes without a key that have only a single child.
Can you write Python code for it?
assistant
#Here is the Python code you requested.

class One(TwoThreeTree):
    def __init__(self, child):
        TwoThreeTree.__init__(self)
        self.mChild = child
        
    def isOne(self):
        return True

    def __str__(self):
        return _make_string(self, ['mChild'])