This is a wonderful exercise which explains the concept of infinite loops.
"A hacker practices on HackerRank until getting to a rating of O(1) read as (Oh-one)"
An infinite loop in Ruby is of the form
Use an infinite loop and call the method coder.practice within it and break if coder.oh_one? is true.
break if conditions in Ruby are of the form
or a one-liner
break if <condition>