Not running properly on Ubuntu

[alphydan]

When launching the notebook on Ubuntu, I get the error:

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
/home/user/[...]/PythonSecrets/SecretCodes.ipynb in <module>()
     91   {
     92    "cell_type": "code",
---> 93    "execution_count": null,
     94    "metadata": {},
     95    "outputs": [],

NameError: name 'null' is not defined

[LeviBarnes]

Thanks for looking!
How did you run it? I did this:

git clone https://github.com/LeviBarnes/PythonSecrets
cd PythonSecrets
jupyter-notebook SecretCodes.ipynb

It started fine and pointing my browser to localhost:8888 pulled up the notebook. Also, I grep'ed for 'null' in SecretCodes.ipynb and didn't find it.

[LeviBarnes]

README has been updated to give clearer instructions.