@Override
	public Character allele() {
		return _allele;
	}
Create a new character gene from the given {@code character} and the
given set of valid characters.

@param allele the char this gene represents
@param validChars the set of valid characters.
@throws NullPointerException if one of the arguments is {@code null}.
jenetics/src/main/java/io/jenetics/CharacterGene.java