>> lower = "`" # predecessor of 'a'
=> "`"
>> letters = []
=> []
>> 10.times { letters << lower.succ! }
=> 10
>> letters
=> ["j", "j", "j", "j", "j", "j", "j", "j", "j", "j"]


# But

>> letters.clear
=> []
>> lower = "a"
=> "a"
>> 10.times { letters << lower; lower = lower.succ }
=> 10
>> letters
=> ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j"]