'Null' value in Python is 'None'

There's always only one instance of this object, so you can check for equivalence with x is None (identity comparison) instead of x == None

stackoverflow.com/questions/3289601/null-object-in-python

Missing data in Python

Roughly speaking:

• missing 'object' -> None
• missing numerical value ->Nan ( np.nan )

Pandas handles both nearly interchangeably, converting if needed.

• isnull(), notnull() generates boolean mask indicating missing (or not) values
• dropna() return filtered version of data
• fillna() impute the missing values

More detail: jakevdp.github.io/PythonDataScienceHandbook/03.04-missing-values.html