Extensions of 'sun' X70546

Statement

You have to program the function below.

Write a function @is_sun_extension(s)@ that given an string $s$ formed by lowercase letters, returns a boolean value pointing out whether we can cross out zero or more letters in $s$ in such a way that the non ruled out letters are, from left to right, exactly ’s’, ’u’ and ’n’

Scoring

The function counts 100 points.

Sample session

>>> is_sun_extension('sun')
True
>>> is_sun_extension('assumption')
True
>>> is_sun_extension('assume')
False
>>> is_sun_extension('russian')
False
>>> is_sun_extension('scouting')
True
>>> is_sun_extension('innocuous')
False

Information

Author: ProAl
Language: English
Official solutions: Python
User solutions: Python