human
I am working on the file "02-PythonWhirlwindCheatSheet.ipynb".
The first task is:
Subclassing is not useful for adding new, stored fields. Instead, simply create a new named tuple type from the _fields attribute:  
Point3D = namedtuple('Point3D', Point._fields + ('z',))

Default values can be implemented by using _replace() to customize a prototype instance:
Can you write Python program for it?

=====
Can you provide a the Python program you requested?
assistant
#Here is the Python program you requested.

Account = namedtuple('Account', 'owner balance transaction_count')
default_account = Account('<owner name>', 0.0, 0)
johns_account = default_account._replace(owner='John', balance=50)
print(johns_account)

# def preparefiles(filename):
#     if os.path.isfile(filename):
#         os.remove(filename)
#     conn = sqlite3.connect(filename)
#     conn.execute('''CREATE TABLE COMPANY
#            (ID INT PRIMARY KEY     NOT NULL,
#            NAME           TEXT    NOT NULL,
#            AGE            INT     NOT NULL,
#            ADDRESS        CHAR(50),
#            SALARY         REAL);''')
#     conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
#           VALUES (1, 'Paul', 32, 'California', 20000.00 )");
#     conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
#           VALUES (2, 'Allen', 25, 'Texas', 15000.00 )");
#     conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
#           VALUES (3, 'Teddy', 23, 'Norway', 20000.00 )");
#     conn.execute("INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) \
#           VALUES (4, 'Mark', 25, 'Rich-Mond ', 65000.00 )");
#     conn.commit()
#     conn.close()