I have the following python code to write processed words into excel file. The words are about 7729

From openpyxl import *
book=Workbook ()
sheet=book.active
sheet.title="test"
for x in range (7729):
    sheet.cell (row=1,column=x+1).value=x
book.save ('test.xlsx')
This is the what the code I used looks like, but when I run it, it gives me an error that says
openpyxl.utils.exceptions.IllegalCharacterError
This is my first time using this module, I would appreciate any kind of help.
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Python – How to import a module given its name as string

With Python older than 2.7/3.1, that's pretty much how you do it.
For newer versions, see importlib.import_module for Python 2 and Python 3.
You can use exec if you want to as well.
Or using __import__ you can import a list of modules by doing this:
>>> moduleNames = ['sys', 'os', 're', 'unittest'] 
>>> moduleNames
['sys', 'os', 're', 'unittest']
>>> modules = map(__import__, moduleNames)
Ripped straight from Dive Into Python.
    
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I thought the process of Python mastery went something like:
Discover list comprehensions
Discover generators
Incorporate map, reduce, filter, iter, range, xrange often into your code
Discover Decorators
Write recursive functions, a lot
Discover itertools and functools
Read Real World Haskell (read free online)
Rewrite all your old Python code with tons of higher order functions, recursion, and whatnot.
Annoy your cubicle mates every time they present you with a Python class.  Claim it could be "better" implemented as a dictionary plus some functions.  Embrace functional programming.
Rediscover the Strategy pattern and then all those things from imperative code you tried so hard to forget after Haskell.
Find a balance.