Determines whether a character is an ASCII lower case letter.
Unlike the standard C library
islower() function, this only
recognizes standard ASCII letters and ignores the locale,
returning false for all non-ASCII characters. Also, unlike
the standard library function, this takes a
char, not an
so don’t call it on
EOF, but no need to worry about casting
guchar before passing a possibly non-ASCII character in.
This function is not directly available to language bindings.