Selects lower-case alphabetic Unicode characters (letters).
Note: this predicate does
not work for letter-like
characters such as:
'ⓐ' (
U+24D0 circled Latin small
letter a) and
'ⅳ' (
U+2173 small Roman numeral four).
This is due to selecting only characters with the
GeneralCategory LowercaseLetter.
See
isLowerCase for a more intuitive predicate.