checking a value exist in a array in python code example

Example 1: python check string not exist in array

arr_test = ["thetung1","thetung2","thetung3"]
title = "thetung"
if title not in arr_test:
	arr_test.append(title)

Example 2: how to check if value is in list python

>>> letters = [a,b,c,d,e]
>>> 'a' in letters:
True