human
I am working on the file "Python/Chapter-07/ListMap.ipynb".
The first task is:
Implementing Maps as Lists of Key-Value-Pairs
The class ListNode implements a node of a <em style="color:blue">linked lists</em> of 
key-value pairs.  Every node has three member variables:
- mKey     stores the key,
- mValue   stores the value associated with this key, and
- mNextPtr stores a reference to the next node.  If there is no next node, then 
  mNextPtr is None.
Objects of class ListNode are used to represent linked lists.  
The constructor of the class ListNode creates a single node that stores the given key and its associated value.
Can you write Python program for it?
assistant
#Here is the Python program you requested.

class ListNode:
    def __init__(self, key, value):
        self.mKey     = key
        self.mValue   = value
        self.mNextPtr = None