`sig
val to_lower : Glib.unichar -> Glib.unichar
val to_upper : Glib.unichar -> Glib.unichar
val to_title : Glib.unichar -> Glib.unichar
val digit_value : Glib.unichar -> int
val xdigit_value : Glib.unichar -> int
val validate : Glib.unichar -> bool
val isalnum : Glib.unichar -> bool
val isalpha : Glib.unichar -> bool
val iscntrl : Glib.unichar -> bool
val isdigit : Glib.unichar -> bool
val isgraph : Glib.unichar -> bool
val islower : Glib.unichar -> bool
val isprint : Glib.unichar -> bool
val ispunct : Glib.unichar -> bool
val isspace : Glib.unichar -> bool
val isupper : Glib.unichar -> bool
val isxdigit : Glib.unichar -> bool
val istitle : Glib.unichar -> bool
val isdefined : Glib.unichar -> bool
val iswide : Glib.unichar -> bool
end`