Incorrect test for None

[hillarygreenlerman]

https://github.com/buschbirk/intro-data-capstone-musclehub/blob/66253a292dbe1c2e164ec5b57ff40c1a6da26ecf/Final%20Analysis/musclehub.py#L213

None objects are tricky. There are several correct ways to test for them:

1. Using is

   foo = None
   print(foo is None)
   >> True

2. In Pandas, we can also use isnull:

   import pandas as pd
   foo = None
   print(pd.isnull(foo))
   >> True

   This idiom is particularly nice when testing an entire column in a DataFrame.

This StackOverflow article goes into more detail about why is syntax is preferred: https://stackoverflow.com/questions/3965104/not-none-test-in-python