I have a dataframe below for example

Name  class  roll   subject
> Ab.   10.   23.   maths 
> CD.   3.    34.   Science

I am using python 3.9

I need to check if a set of columns is present in the data set and if any columns is missing the column will be created and null will be assigned and should be dynamic

Example 
I am checking if columns [Names,Class,roll,school,subject ]is in the dataset

If a column is not present it will created output will be below

Name class roll school subject 
> Ab.   10.  23.   NaN.   Maths
> CD.   3.  34.  NaN.    Science