func newLetter(r rune) (*Letter, error) {
	if r < 'A' || 'Z' < r {
		return nil, errors.New("letter must be uppercase and between A and Z: " + string(r))
	}
	l := Letter(r)
	return &l, nil
}
// newLetter creates a letter from the rune.
newLetter creates a letter from the rune.
// newLetter creates a letter from the rune .
func newLetter(r rune) (*Letter, error) {
	if r < 'A' || 'Z' < r {
		return nil, errors.New("letter must be uppercase and between A and Z: " + string(r))
	}
	l := Letter(r)
	return &l, nil
}
func newLetter ( r rune ) ( * Letter , error ) { if r < 'A' || 'Z' < r { return nil , errors . New ( " " + string ( r ) ) } l := Letter ( r ) return & l , nil }
newLetter creates a letter from the rune.
newLetter creates a letter from the rune .