As Pierre wrote before sometimes you need functions you usually would say "no, you’ll never need this, this task can be done with just one line PHP" but later you see "Okay, now I could use it".
We had such a situation a few days ago: Thorsten once complained that PHP has functions for everything but no is_negative(). We all in the office, including Pierre, knew that we don’t need such a function since everybody should be able to do this using the < or > operators and would neeevvveeeerrr demand it. A few weeks later, Thorsten and Pierre are working on a project where they are doing some complex calculations and Pierre recognizes the need for such a function. As a result I can present you our companies new friend: is_negative().