More sensible output for repeated(x, 0), repeated(x, 1).
char_range gives more sensible output when lo == hi.
digit -> ascii_digit
updated example 1:255 -> 0:255
number_range works for cases where the first digit is all the same number.
Output simplified where there are repeated digits, i.e., [0-9][0-9] -> [0-9]{2}
Number range example.