public static CharacterGene of(final CharSeq validCharacters) {
		return new CharacterGene(
			validCharacters,
			RandomRegistry.random().nextInt(validCharacters.length())
		);
	}
Create a new CharacterGene with a randomly chosen character from the
set of valid characters.

@param validCharacters the valid characters for this gene.
@return a new valid, <em>random</em> gene,
@throws NullPointerException if the {@code validCharacters} are
        {@code null}.
jenetics/src/main/java/io/jenetics/CharacterGene.java