how to check if not null in python code example

Example 1: python not null

test = "hello world"

if test is not None:
  print("test is not None")
  
test2 = None

if test2 is None:
  print("test2 is None")

Example 2: python if not null

#variable
var = "hello python"

#check is not null
if var is not NaN:
    print('Var is not null')