func IsLetterUnsafe(r rune) bool {
	return isUnsafe(letter, r)
}
IsLetterUnsafe is the unsafe version of IsLetter.
package runes
import (
	"unicode"
	"unicode/utf8"
)
func IsControl(r rune) bool {
	return unicode.IsControl(r)
}
func IsDigit(r rune) bool {
	return is(digit, r)
}
func IsDigitUnsafe(r rune) bool {
	return isUnsafe(digit, r)
}
func IsGraphic(r rune) bool {
	return is(graphic, r)
}
func IsGraphicUnsafe(r rune) bool {
	return isUnsafe(graphic, r)
}
func IsLetter(r rune) bool {
	return is(letter, r)
}