This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
Think about the steps involved: (range 0 10) - which is the same as (range 10) by the way - produces a sequence of numbers; you want to convert each number in the sequence to a string; then you want to convert that result sequence into a set.
Sounds like map and set.
Do you know how to convert a number to a string?
I'm not just giving you the answer because I think you would benefit from going through the steps and figuring it out - and this is a very simple problem so if you don't understand how to solve this, you will be lost when you encounter harder problems.