cities = [
    'chennai', 'delhi', 'madurai', 'pune', 'bengaluru'
    ]

cities

['chennai', 'delhi', 'madurai', 'pune', 'bengaluru']

def is_south_indian_city(city):
    if city == 'chennai' or city == 'madurai' or city == 'bengaluru':
        return True

    return False

new_list = list(filter(lambda x: is_south_indian_city(x) , cities))

new_list

['chennai', 'madurai', 'bengaluru']